because some classes have to be "harder" than others. Why do DPS not really have to worry about enmity generation anymore? Why does it only have to be tanks? Why don't healers get DMG buff traits but BLM does? IT'S NOT FAIR AND I DEMAND EQUALITY!!!!!
So just make 1 class that can wear any armor and use all skills so everyone will be happy. Oh yeah, they did that in FF12 and the majority hated it.