I enjoy the mechanics of the one exotic per category system. My exotics become more central to my specific build and having an insane number of special perks would destroy the delicate balance that is fundamental to the games core combat system. As others have said before, a third subclass featuring the respective elemental damage that was omitted from each initial class will be a great addition, and seems most like something bungie has preplanned for release at a later date. I say that it's most likely because the third subclass slot still exists and the bizarre lock function was remove after beta. How locking a subclass for a stat increase would be smart is not obvious to me. I like the versatility I have in switching minor perks.