So like DDR?
Its the way it is because of EBA-Authentic skinning (although I think even in EBA, the applause didnt play or something different happened if you got a c or d. I havent opened up the game in a while though)
Itd be fun but itd have to be a thing thats developed in whatever new skin is coming out, since they have to program like "If player achieves x rank, play xrankapplause.wav"