If it's 2 bars for a Max Cancel Neomax, that's either a 3 or 4 bar commitment, depending on if you did a normal or EX DM, to get to the MAX Cancel status.
It'd be a nice buff, but it wouldn't be that much of a difference. Take for instance, Raiden. How many EX Shoulders does he normally use in his KILL combos? Or how about Leona with EX Moon Slashers?
I guess the scariest things here, would be the fact that you could now squeeze another EX move into a combo, before MAX cancel -> Neomax. That could lead to some even crazier juggles, and lead to a wider range of the cast having high damage combos.
If a max cancel ending off am HD mode string of normals cost the same as a naked Neomax, and they end up doing not-too-much different damage, due to the early hits scaling the MAX stuff down, I think the change would just make fights more interesting, in the end. The strong wouldn't get THAT much stronger, and the weaker would get to use their full toolsets more actively, which would help cover some of their shortcomings.