Just finished off my 1st boss and got it's Crimson Seeds, and after looking at the Wiki I'm wondering WHY IN THE HELL WOULD I WANT TO PLANT THESE!?!?! :P

Is there anything else like that I should be looking for that the game presents as a gift only to end up being totally evil?

When you generate a world, it randomly decides between giving you the Corruption or the Crimson. Both have exclusive enemies and an exclusive boss, along with their own exclusive drops, which may be unavailable to you through normal means in a single world. If you take crimson seeds and plant them in a world that has the Corruption, however, and you cultivate it enough that enemies start spawning in that area, then you get access to the drops from both. You won't gain access to the exclusive ores from the other side, but the normal enemies and their materials will be available artificially. What would it do for you in your crimson world? Probably not a lot, since I'm sure that you don't have a shortage of crimson in the world. :P

The only thing that immediately comes to mind that would be super-dangerous is trying to use a boss-summoning item to summon a boss that is alive and attacking you at that moment. When trying to use most of the items, they simply don't work until the boss is dead or has left, but one item in particular will decide to do something like 1000 damage instead of simply not summoning the already-present boss. So, as long as you don't try to summon multiple copies of the same boss at the same time, then you'll be able to avoid that particular effect and be fine, I think.

the only real uses I know of is either to create a artificial/self made Crimson biome for farming purposes or to craft unholy water to help push back the hallow biome come hardmode, well till you get the steampunker npc since she sells a gun that will convert any biome to any other biome of your choice(pending you have the right solution)

Corrupt Seeds are used for making Unholy Water, but there's no Crimson equivalent. They're just for spreading the Crimson, if you choose to do so.

There are a few reasons you might want to do that. If you make a "controlled" Crimson biome, you can safely farm drops using traps and the like, and you can have a safe renewable source of Shadewood. There's also a painting that the Painter only sells when he's in the Crimson (and another in the Corruption). The seeds aren't super-useful until hardmode, though. There are several rare items like key molds or Vitamins that you'll want to hunt for, and there's also a Meat Grinder that will let you turn Crimstone into Flesh Blocks, which can be used to create all sorts of gory furniture. All of these things can be done in a natural Crimson biome, but there are a lot of advantages to setting up a farm of your own.

Ultimately they're just another tool to help you make your world exactly how you want it to be.

You just reminded me what a pain in the butt searching for the ingredients of the ankh charm were.

I've made 6 so far and Vitamins/Nazars are the ones I've had most trouble getting.

They were troubling in the Vita version.