The holy trinity? Because if your going to be True to it you can't Make anything that doesn't fit it or Otherwise Limited Jobs type.

WHY? Yoshi-P said in an interview that GunBreaker came early and he went Dps because he wants to Focus on Balance with Healers (how long that will take is another issue. He has gone on Record saying White Mages need to be Pure Healers and the rest go in line to there place in The Holy Trinity " you can't work outside that line").