My only guess is that at one point in time the game functioned the way you hoped it would and it either caused too much arm fatigue or they thought it was distracting. I could go either way, but in the end I get the feeling that the final scheme was better for the game than an extremely elaborate means of interaction. Maybe a compromise would have been best... The finishing moves would be nice to have special arm motions for, and then the standard jabs/slices could remain generic/analog controlled.