But Destiny is a game built around Guardian abilities. Grenades, melees, and supers are just as important to one's arsenal as their weapons. Because of this, players should, in my eyes, be able to rely on their abilities just as much as their gun. All exotic armor would do in this case is bolster those abilities, in the same way that a weapon's exotic perk improves the functionality of that weapon.

Well the thing is that certain exotics basically allow classes to take over the roll of each other. For example the ram allows warlocks to take over the roll of the Titan as a tank. The twighlight garrison allows Titans take over the roll of hunters as most manuverable. The tarantella allows hunters to get their super and grenades incredibly quick. It's to prevent people from being forced to run a certain class with certain exotics. Basically it's about balancing the classes as much as possible.

Like I said in the OP: if it's a select few exotics ruining the fun for everyone, just ban the ones causing the issues. Creating a banlist for overly-potent exotics would keep everything in control while also boosting build diversity. For example: The Ram Twilight Garrison ATS/8 Tarantella Crest of Alpha Lupi/Light Beyond Nemesis Voidfang Vestments [b]in Elimination[/b] ...and etc until the remaining exotic pool is balanced enough to be considered fair. I believe there's already a few banned exotic weapons... why not for armors as well?

Because it's A. Just simpler to ban all exotic armors and B. Exotic armor pieces are designed to give you some kind of an edge over your opponent so pretty much no matter what if you're running an exotic armor piece and the other guy isn't, you'll have an advantage. Also The only banned weapons really are class exclusives and that's mainly due to the fact that tlaloc is very nearly unbeatable when the user has their super. Thorn and last word are often banned but it really depends on the group you're with.

I don't think players will mind the complexity of a banlist. Plenty of other games have a banlist in competitive play and they're just fine. If exotic armor wasn't banned, I don't see why anyone [i]wouldn't[/i] be wearing it. It's pure benefit, and loosing out on it would be pretty foolish. That being said, the entire purpose of using exotic armor is to give yourself an edge over your opponent. It's the reason why choosing what exotic to employ is difficult; there's hardly a clear "best option." For example, your Claws of Ahamkara gives you a second melee, but your opponent's Armamentarium gives him an extra grenade. In CQC, you'll probably beat him, but at range you're at his mercy. Depending on your playstyle, you might switch to Nothing Manacles to compete with him at those ranges. It's situations like this that add a layer of depth to the game that wouldn't be there otherwise. (As a side note, I think that only very specific exotic weapons should be banned. The class exclusives, "primary specials," and Icebreaker in particular)

Again it all goes back to keeping the rules simple to understand and keeping the classes as balanced as possible.