This is not a true obstacle, even if this was the case Team NINJA is here just for developing a balanced version of the characters to include in the game (if they wish so).
The opposite reasoning could be done with Tengu being really bad and useless in DoA4: again this didn't stop TN to create a new moveset in Doa5U able to be seen as faithful and however an evolution of its old one.
If they managed to come up with Noka, Marie and Momi's moveset after the game was completed, I don't see how Genra couldn't be redesigned. It's be a big bummer for him to return the way he was in Dimensions.