I'm pretty sure it had something with the Korean localisation met a hurdle (legally), making it so that they couldn't use the original themes AND stages from Reload. So they had to improvise and thus hired N.EX.T, a Korean Metal-Band, to make new music, composed by Shin Hae Chul, for reworked stages in the game.
Here's more from that band, btw: http://www.youtube.com/watch?v=R9JN-HrdfT4
Btw, I gotta say, kudos to that localisation company for doing so. Showing they won't let nothing get in the way of getting the game out. I have nothing to verify this though. It's just something I recall reading somewhere (on Youtube, I think), so I might be wrong.