Because the fights in IWD are generally more of a clusterfuck than they were in BG (I ragequit on the second game, but this seems to be the case for that game as well from my limited experience). BG tried to keep combat balanced to the point that soloing would be a challenge, while in IWD, MC classes are hardly overpowered, they are almost required, and even then some of the later fights can get ridiculous; even with the most min/maxed Paladin, Dwarf Fighter, Human Mage, Gnome Illusionist/Cleric, Elf Fighter/Thief, and Bard, I still got my ass kicked on a regular basis. The only reason the game got easier at all was that I leveled up by taking on the expansion material and changing to easy mode part of the way through to maximize the XP gain to give my characters a chance against the horde of Glabrezu that routinely stomped them dead.

This is actually one of the bigger problems with IWD; BG tries to have pretensions about being an RPG in that used appropriately balanced action scenes to provide challenge when it wasn't trying to build a world in furtherance of telling a narrative (I personally debate how well it did this, but that's neither here nor there); everything in IWD is in service of getting the player into large battles that contain several times more enemies than the norm with obscenely high power levels, to the point that the game is more accurately described as a suicidal wargame sim with RPG elements. It's as if it were designed by people who play D&D to do nothing but min/max the system and simulate tedious fight sequences that put even the most twinked out character through the ringer.

Dude, let go of BG. This game, as noted by Jonesy, isn't BG, even though it's also built on the Infinity Engine. It's designed primarily around combat, not the RPG elements and is therefore a tougher game. You really need to stop trying to force the square peg of your desire to play it as a 2-character party into the round hole of a 6-character party design. If you find it too hard to play with two characters, then you have three choices as far as I can see:

1) build a bigger party to cover the weaknesses
2) go with two multiclassed or dual classed characters that cover the necessities (as pointed out earlier in this thread)
3) move on to another game.

I see no reason to torture yourself by trying to force the game to be something it isn't. Either accept that you're going to have to change your party size or your character classes (or maybe both) or toss in the towel.

Im sorry for wasting your time. I understand what you mean. Im going to work on another game. It's obvious that I brought this on myself by not listening to sound advice. I'll play another game and not worry about wasting everyone's time with my own wishing that this was BG and or Planescape. I hope your not too angry at me for being such a dick :)

You were hardly a dick. Furthermore, you have nothing to apologize for; you bought a game that ran on the D&D system, which is an RPG system, with the completely reasonable expectation that it would actually be an RPG that can be won without resorting to metagaming and min/maxing. Instead, you got a wargame that demands that you abuse the system by focusing solely on min/maxing and other things that most DMs turn their nose up at. If there is any blame to assign, it goes to the producers of the game.

Oh hell, no need to apologize and you were by no means a dick. I hope my post didn't come across as me being angry because that was in no way my intent. I'm glad to try to help out, but it really seems that this game just isn't going to fit in with your style. Unfortunate, as I think they're fun as hell. Anyway, if you decide later on that you want to try it again, by all means feel free to ask for some advice. We're always happy to toss out some suggestions. :)
I have to disagree with this. You don't have to min/max, metagame, or abuse the system to get through the game. Although if you're planning on playing with less than a full party, then you may have to resort to those practices, depending on what you choose to go with.

Nonsense. The game does by no means require meta gaming or min/maxing. I have completed it several times, including one solo playthrough. I never min/max, I don't metagame and I don't spam spells in every encounter followed by resting, but instead only allow my party to rest once a day.
It does however help to have some patience, both to learn the system and to plan your actions.

The game is rather poorly balanced, though, so some areas are harder than others and can be a bit frustrating.

I created a full team comprised of a Paladin, Dwarf Fighter, an Elf Fighter/Thief, a Human Mage, a Gnome Illusionist/Cleric, and a Bard, which seemed to be a fairly balanced party (which I have confirmed by rereading the AD&D 2E system); I initially tried to not min/max, but after getting my ass handed to me reliably before getting to the first room of the cave, I decided otherwise and recreated them with the most obscenely min/maxed stats (the Paladin and Fighters had as close to 18/00 as they could get). Off the bat the party should have been able to lay waste to any balanced campaign.

We went into the cave and still got destroyed, even with using the most defensive tactics possible. The only way we were able to survive was to send the thief ahead (which is fine) and have them squeeze between two monsters so tightly that I'm pretty sure the only reason they didn't raise an alarm was because they were getting distracted by the free lapdance they were inadvertently getting (which was legal according to the rules but had absolutely no business working and that no DM would allow the players to rely on) to map the area out, then having one person draw each monster into an ambush (which was a sound strategy), relying on the AI for other monsters in the room to stop pursuing us once they couldn't see us and the pursuing monster refusing to call for backup (again, legal by the rules, but completely nonsensical and the sort of thing any self respecting DM would not allow).

The final room was especially embarrassing in that regard; we could either go on an offensive and charge in (which got us killed), enter the room and play defense at the cave mouth (slightly less suicidal), or have the party in the previous room while one of them went into the next room hooting and smacking their bum to draw monsters in by ones and twos, while their barely out of sight comrades decided to not provide aid despite the fact that they could obviously see something had the orcs excited. When we finally moved in and saw that the Ogre hadn't budge an inch despite the orcs surrounding him running after us and promptly dying in an ambush in the corridor, I almost felt bad about killing it because it felt like picking on a mentally challenged person.

There you go. My first large scale battle, wherein even with the most min/maxed party had trouble and resorted to abusing a hole in the AI to win (a tactic that I notice is often brought up with regards to the final fight in BG, so it's not like this is something new). This proceeded to repeat itself for virtually every fight in the entire game. When the only sane option in that kind of scenario is to abuse a computer's rigid interpretation of the loose AD&D 2E ruleset and the resulting moon logic that such interpretations produce, then I think it is fairly self evident that IWD is a game that all but requires munchkinizing.

tl;dr: Now this is a story all about how my game got flip turned upside down, and I'd like to take a minute, just sit down, Blaine, and I'll tell you all about how IWD makes you metagame. In the character creation screen born and raised, rolling ability scores is where my chars spent most of the pre-game day, made a six-pack of balanced guys who were up do good, and start making trouble in the villains' neighborhood. I got in one little fight outside a cave and my guys got axed, so I said "you're going back to char creation to get yourselves min/maxed." I wound up at the start again, and things were very clear, like I couldn't expect non-twinks to become more than a bloody stain here. If anything I could say that this development was pretty lame, but I thought "nah, forget it, I'll play the game." I fought all the way up to the cave my guys (six because I couldn't have eight), and I said to the Ogre, "yo ho, smell you later", looked at the arena, I was finally there, to game the AI by drawing them individually away from their allies who just didn't care.

While I generally disagree that you need to min/max to beat IWD, especially on Normal and below, I have to give you props on your tl;dr version. That was freakin hilarious. Bravo, sir.

Hilarious to read.

But that aside (and I hate to put it his way), but if you got your whole party waxed in the orc caves, then your tactics are suspect. Play it like you would PnP: send the thief in to scout the area. Once you know what you're facing, plan out your tactics accordingly: judicious use of a disabling spell such as Sleep from your mages, have your warriors mop up whatever isn't affected by the spells, while the others toss in some ranged attacks.

I have trouble believing the orcs and ogre didn't all attack you at once in that last room. Every time I've played it, as soon as one of them sees my character, the whole room rushes the party, ogre and all. The AI calling for backup is one of the things that people applaud about the game. It's not like BG where you can use the fog of war to lead a single mob to his doom while the others wonder why Bob disappeared and never mind the sound of slaughter and battle 30 feet away.

As far as min/maxing, I'm beginning to wonder what you mean about this. Do you play warriors without high STR? Or mages without high casting stats? Because even though you don't need to min/max in this game, you do need to set up a viable character: i.e. high scores in their prime stats.

I have played P&P D&D, and for reasons I have mentioned elsewhere on the forums, using P&P tactics in this game is a bad idea because of how the game applies AD&D 2E, rendering some tactics useless and others diminished. I assure you, I did send out a scout, but they were able to do their job only by doing stuff that they had no possible way of doing (see the example of squeezing in between two enemies while certainly coming into contact with at least one of them). As for the last room, I assure you that while the AI in IWD might be better than in BG, I was able to attract targets almost one at a time to come back into an ambush, and the Ogre had yet to do a thing when we stormed the room at last.

As to min/maxing, I don't play unintelligently; a caster should have a high appropriate mental stat, a fighter is going to need good Dex/Str/Con, etc. Where it gets ridiculous is when I have to reroll my stats until I have enough spare points to assign an 18 to all appropriate scores for that class while leaving their less important stats at their bare minimum (Char might not be a dump stat in P&P, but in this game it pretty much is, barring the Paladin and Bard) with maybe a few points assigned after I got 18s in all relevant stats for each character (17 Wisdom for the Gnome Cleric/Illusionist). Playing a generally powerful but balanced character is viable in P&P, but in a purely combat oriented game like IWD, all stats that don't boost your combat effectiveness are so much vegemite.

Do you use your Thief for other things than scouting? Against the orcs I found a good tactic was to move him in position behind one of the orc archers and backstab the orc, while the "tank" rushed toward another archer and the rest of the party use missils weapons, while the thief runs to a dark corner to hide in the shadows again.
It's not that hard to defeat the orcs without using any spells, but saving them for the Ogre.

Im not trying to defend but this is true. I had a few monsters who simply didn't notice me and just sat there. Its not always happening but it is very useful when it does. I figure maybe he just hit too much of the sauce last night as it happens sometimes with giants and verbeegs.

Been there, done that, bought the T-Shirt. Even with that set of tactics, I was looking at roughly even chances of multiple characters dying. And this was just the opening part of the game, TotLM was just insane by comparison; the AI for the Glabrezu had no problem tracking us down the moment it spawned offscreen, nor did their summoners have any problems spotting us way before we could see them and start calling down the thunder.

Well, I think playing with two characters can be a lot of fun, and I'd actually say try lowering the game's difficulty to one or even two categories below average. This way, you can have the classes you want, no matter who they are, and you should be able to go through the game with a fun level of challenge.

Since you don't want to multi-class, and you don't want optimum choices, I can't easily say what you should pick. I never went through the game with two characters, anyway, but the story is good so you shouldn't skip it.

What classes do you want most?

Do you want a solo thief if no multi-class? Playing with no thief will present its own challenges, from traps. The classic choices would probably be something like one ranger and one mage.

This is a very viable option; however, you will want to turn the difficulty all the way up or down if you start tinkering. Normal gives the least experience, and moving to either extreme gives more experience. Not exactly as balanced as BG's system that gave out lower XP on lower difficulties and scaling upward (until it hit normal, providing no incentive to play on hard outside of masochism), so going to either extreme is the most sensible option if you are looking to maximize survival of a small party by outclassing everything that much quicker.