So my personal preference, which is flexible and highly personal is wrong then?

Just a few thoughts...

1. Many games -- D&D being one -- exaggerate the prevalence of precious metals in the game world to allow players to more easily find hoards and gain money. How fun is an adventure if you do great deeds and are still rather poor?

2. While gold coins would have been uncommon for the regular person in medieval Europe, silver and bronze coins were indeed in much more common use. But do you want multiple kinds of coinage in a game? Some have it... but most leave silver and bronze to crafting. (aside... in the modern world silver should be the most valuable of the 3 for its dual use as both a monetary and industrial metal)

3. Originally coming from companies specializing in gambling, it makes sense that many would incorporate gold drops similar to a jackpot reward. I'm reminded of the distinct "jackpot" sound of coins clinking (and a "tally sound") in Dragon's Dogma when gold is picked up... similar in my mind to a slot machine. Again, inserting "exciting" elements of the gambling experience into the game world.

So with that said..

... I don't tend to care whether it's gold, experience, or items... as long as it's useful in that particular RPG. If trading or crafting is a significant part of the game's experience, I'm fine with items that can be used or sold. But if the game's mainly about questing, I tend to want gold and experience.

Do I care that creatures drop gold?

Not too much... but... I can respect an RPG that has gold in the environment (ie a creature's lair) and leaves experience as the reward for besting said creature.

I want my baddies to be veritable gold piñatas

In my opinion, monster loot should only provide you with the most basic rewards.
The best solution still is to introduce a second premium currency. In order to obtain it in reasonable amounts and buy those tempting weapons and shiny armor pieces, you'll have to charge your real credit card. That way, players will get a real sense of accomplishment and ultimately more fun out of every game.
MMORPGs have shown us the true way. Now it's time for most single-player games to follow suit.

(Following up on this thought, the implementation of a reliable micro-payment API would give our beloved Galaxy client even more use and crank the user experience to 11. GOG would of course directly benefit by taking a significant cut of all transactions. So it's win-win-win for everyone!)

When you think about it, it's equally implausible that a giant spider would have staves for entrails

Except that a player could just hack their save file to get the benefit of the transactions for free.

If there's any mechanism to prevent the player from just hacking the save file, that would be a form of DRM, which would go against GOG's DRM-free principle.

In a perfect world, the only value in gold would be as electronics parts in all the most important machines like telescopes and power grids.

As for how it drops from monsters, just world-build creatures that eat gold like skags in Borderlands.

They're money spiders.

(Credit to https://tvtropes.org/pmwiki/pmwiki.php/Main/MoneySpider.)

The way real life worked in the past / works now:

Loot reselling and specific monster parts huntin through quests or main and secundary quests completion.

Monsters only drop their parts after being killed.
Some specific monster parts have more value based in the game economy of monster parts.
This is something a really old game did well based on in-game Seasons: Monster Hunter Dos (2).

In Monster Hunter your gold comes from killing monsters through 'quests' and you use monsters parts for everything: From building new equipment, upgrading equipment, to selling extra valuable monsters parts for merchants.
In "MHDos" which had a seasons system, some monster parts were really valuable in some seasons because merchants were or were not in need of it in that season.

So there's an element of strategy on hunting a 'Warm season" only monster and store its parts to sell them later in "Cold season" for a higher price.
Because of this, there are always ways of optmizing gold income through main and secondary quests completion.

Heh, sounds like Bard's Tale and the 'random wolf'.

Regardless, dropping gold is just fine as a sack. Why? Because you don't need a ton of different junk items for 'wolf teeth' and 'wolf pelt' and 'wolf trophy' and then duplicate that for a dozen other monsters when just a gold value will do which represents not having a bunch of inventory space filled up with crap you intend to sell anyways.

Yes it's not very realistic. But this is video games we're talking about.

I prefer your second item, "inferred value". Which is also how I run my TTRPGs: It's stupid to itemize out gems, artwork, "skin them for fur", etc. I just convert direct to GP value. Treasure's already hard enough to manage in a TTRPG that the extra layer isn't additive.

Video games, I also prefer just the "inferred value". Explain it during loot collection, poof. Problem solved. Have implied "quick visit to merchant and back" or whatnot. If required, abstract inferred loot into a single currency of its own that easily converts to gold when you sell (rather than managing individual crab claws, spider fangs, bat wings...)

It even opens up a game mechanic where, in some areas/dungeons/plot points, it doesn't happen until you "cash out". It'd still just show as "gold in waiting" or something (maybe with a limit, depending on the kind of dungeon and systems designed around it) until the zone is complete. [This ties nicely into dtgreene's other recent thread on "do something explicit to level up", but with gold. Which, BTW, it is rather silly of the game auto-levels you with instant XP, but makes you go cash in barter goods for your GP] The game still doesn't need to track individual "barter goods" as what they are, just a single abstract pool that cashes out at that point.

On top of this: I pretty much universally hate "crafting systems". I understand it when they do it for "ingredient not available yet to make this gear yet", but, in those cases, just be overt "not yet available". Collecting uncountable resources (and inventory management that comes with it) is a poisonous curse that really should be excised from most games to increase their fun. Newer games have gotten better about it: fewer resources, easier inventory management... But it's still not something that feels good to me.

The "FU" system you list doesn't sound so bad, actually. It could be an interesting trade-off if properly designed around.

Tangent on ARPGs: A good innovation that Torchlight had was its "sell from where I am" pet. It took too long and was too fiddly, but it was step in the right direction. Now, I totally understand the core game design and why they (ARPGs) did/do it as they do: force player breaks to go to town to sell things to work on pacing of the game and whatnot. But, all of them, at a certain point you just start ignoring all the loot. And that's irritating. (Optional) Automatic conversion should become the norm. They also did it for the "player is carrying all this stuff" thing. But, hey -- the player can already carry a dozen sets of full plate armor. That unbelievable ship sailed. Something so often overlooked, yet so important. I'd rather spend my braintime on tracking quests and manually navigating (something most games have gotten rid of nowadays with their ultra-precise quest markers) than arcane sub-systems that aren't bringing anything to the table greater than their cost.

Grim Dawn: It is all the more irritating that you have to manage craftable "upgrade trees". And sometimes as you're building up to make what you want, it'll use up your already-made lower level things as a component that both part 2 and part 3 of what you're doing so you'll have to re-craft them again. Fortunately it's just menus and auto-grabs from stash... But it's still an annoyance. I find myself penciling down what all I need to do when I'm doing higher tier crafting. And that's something that shouldn't happen.

I'd never do that in a tabletop game. I feel like it would be way to simplistic and feel too... well, "videogame-y". Besides, it can be quite important whether the players are carrying a sack of gold or a bunch of wolf furs or precious gem. Unlike in a video game, such items are not just currency or barter, they can end up being used in a number of unforseen ways depending on what happens, and what the players come up with. I feel like it would rob players of agency to just convert everything into coins.

The logistics of loot management (in "D&D style" games that have loot) make everything you discuss an impossible task. A verifiable white elephant. And, even if you have someone who loves spreadsheets to manage loot for everyone, it's just not actually fun and doesn't come up like you suggest it might in any good play. And boy does it slow the game down to ask people to track crap like that. Every encounter ends with 20 minutes of "butcher the animal and come up with what it has and what might have value", so no actual adventuring happens. (And, yes adventurers should be adventurers. Not merchants, not craftsmen, not hunter-trappers. They'll dabble a bit into various things or have "when not adventuring" hobbies.) Otherwise it's not an exciting game to spend time together 'round the table.

Sure. I mean, unless you and your players have just a tiny bit of imagination. Just simply trying to pawn a painting can become an unforseen adventure in its own right, that won't happen if you just tell them "it's a 100 gp guys". A silver chain picked up weeks ago can prove crucial to a quick thinking player against some silver-averse monster. I don't see Geralt fighting the striga with a sack of gold. Not to mention how artifical that instant exchange feels. Zero immersion.

What's supposed to be "impossible" about it I can't even conceive. I don't know what crazy amounts of loot you're used to giving your players, or otherwise how lazy hey are, that writing down "a golden sceptre, two silver chains, a silk gown and a signet ring" will take you 20 minutes and be impossible to keep track of.

Anyway, you do you, everyone should play tabletop rpgs the way it suits their group best. If you and your players like it simplified to the max to focus on nothing but combat and quick cash - power to you. But please don't act like your way is the only valid one.

Funny, we had an adventure based on a similar situation. It was my main adventure of the week, though the group didn't know it at first. They wanted to sell loot, but it came with a curse from the original owner that marked it as stolen. Reputation points in the region dropped and they had to try to track down the owner and hope he'd offer a reward, and possibly help clear their names. A ton of fun.