I am going to play devil's advocate a little here..

The issue I have with instrument emotes is that presumably the songs would play while the zone music is playing as well.. And that will just simply sound awful. And if it interrupts the zone music (and stops it) then that's even worse.
Further onto this, if you want to toggle the sound fx of the instrument emotes off, you would likely have to toggle off "voices" which means you will lose out on all of the normal emotes and battle voices..