I also would like to see them add a way to disable battle music and FATE music.

Some other sound options I'd like to see below:

an option to turn off "crowd noise" in the ambient noise section (I love the nature sounds but really dislike the loud obvious crowd noise loop)
an option to turn off the short music clip that plays when you start/finish a quest, start/finish a retainer venture, accept/finish a leve, turn in grand company provision (hearing this over-used sound clip every 2 mins or more gets really repetitive/annoying)