I dont know if this has been posted before but here we go. I just had a random thought the other day while playing diablo, 'why doesnt destiny have set items'? The answer would be because of the exotic item system, and they dont want to unbalance anything and adding in completley new perks to the system could mess things up. But then i thought what if they had legendary armor sets, when you find 5 items of the set it unlocks its final perk and it could grant an exotic perk. This would allow you to also keep your exotic armor of choice, for an example you could have a hunter wearing the boots that give you an extra jump and still be able to have a 4th golden gun shot. Its a kindve complicated idea, but i think it could work until something better is in place.