Armor seems to favor specific subclasses either by virtue of an exotic perk, subclass armor perk or a element multi kill perk. The more a person plays the more they will focus on stats as well and it's a b***h to re-balance your build when you change subclass, add an exotic for flavor and end up on tier 10 in stats. Adding the loadouts wouldn't need any new features in the UI either. Just select your subclass and the pre-set gear rotates with the current gear.