I think in the case of a full motion sensing fighting game, the question would be, who would really want one? Far as I know, most gamers aren't the martial art masters they like to portray in games like Tekken (me included).
However, motion enhanced controls I could see if they did it really well. Even that would take a lot of work to get good at, since reacting by pushing buttons is much easier than reacting by blocking with your actual arm...
I don't think games will ever get to this point, because then it moves from a game into a martial arts simulator =) (though that would be pretty sweet).







