I really enjoy FFXIV's soundtrack -- it's great and this is undeniable.
I remember when I first heard "Thunderer" (Lahabrea/Twintania track,) I was so into the music. Now, I can't stand the song. In fact, I have the exact opposite sentiment to the song now. When the song starts up the feeling is akin to chewing on rusty nails.
There's a philosophy in radio that you can actually shorten the lifespan of a great song if you play it too often. And, it is inevitable that eventually people will bore of a song after they've listened to it too much.
Unfortunately, FFXIV kills all of its great tracks incredibly quickly but forcing players to loop the same song over and over during the many hours they spend in the game.
FFXIV's music would be a lot more powerful and engaging if people weren't forced to burn out of the same song literally within the first few hours of attempting a new encounter (the same can be said for that main battle theme that plays over and over in every zone, city themes that loop etc etc...)
Here's my suggestion: a jukebox function. Allow players, through the UI, a function where they can unlock and choose with background music they want to listen to. Maybe even create a playlist? A reward, for example, of defeating Ramuh could be the option to now play his song through the jukebox wherever in Eorzea you'd like.
I hesitate to say this too, knowing people's knee jerk reactions to fan service and micro transactions, but you could even include the ability to purchase and add songs from previous FF titles into your jukebox.
I honestly think that with the proper development and implementation this could turn into a feature that would give FFXIV a very unique feel to any other MMORPG out there while breathing life into the many tracks that FFXIV and other Final Fantasies have to offer.