Don't forget if you make it so people can bind different attacks to different keys without any movement inherently involved, you're gonna make people a whole lot harder to read in multiplayer.
One of the major things that sets a bot apart from a player is how everything they do seems to be super spontaneous, and comes out of nowhere - because they're missing that little microwiggle which you do pick up on to instinctively feel the move they are going to make.
You ever fought somebody playing inverse after not having done so for weeks, and all your reflexes seem out of whack? That's largely why. Your mind can feel what they are gonna do just before they do it - all that movement adds to the players... combat fingerprint, i suppose.
You let people have the different attacks to their different buttons... Other than the potential more-derpable animations that may result, you're also removing that micromovement that, in my opinion, is important to keep.