Well the dev specifically said "Hard Mode" dungeons, which do have looping music. I also recall another dev, on a different thread has said that dungeons before 2.2 will not have their dungeon themes redone to loop.

Also, Lost City of Amdapor doesn't have a battle theme, save for the mini-bosses and the final boss. Why are you implying a battle theme does override it? Did 2.3 change something?