A better and simple explanation.
Nobuo and Hamauzu have diferent styles, and I like Nobuo's more.
While I agree on what you said that XIII (and XIII-2) have amazing battle themes, I didnt like the overworld music. Not for being bad, the music itself is really good, but it doesnt fit with such a (suposed) emotional story and it didnt get to put me inside the story, how Uematsu did.
That's what I was talking about when I said magic : /