In the monotonous nature of this game, can't we have a random battle music generator? To have different battle music every time we engage an enemy. The number of battle music can be limited to what you have already heard from where it came from so it can be spoiler-free (lol). This doesn't have to take effect in battlefields because we fight in them a lot less than elsewhere where an exp party and farming takes place.
Of course, there would be the ability to filter this feature on/off. It would probably be off by default, like how it is with bell sounds (to my amusement).