It looks like one of the features that amped up the excitement of some game players is not as good as it was originally thought. Gamers were hoping that with the Xbox 360 they would be able to play any music they wanted during any game they wanted.
Sometimes I like to play Halo, but I want to listen to some hard rock or alternative to get my blood pumping, but as with the original Xbox, developers will have control over the music if they so choose.
Developers play it down as they feel they put effort into setting a mood and use the music for game cues that will be lost if players have control over the tunes that play while gamers are playing their games.
I disagree as I think gamers are more in tune with what they want to listen to than the developer ever could be. If I want to listen to disco while playing a horror game like Doom 3 or F.E.A.R., then I should be able to.
Source: Eurogamer via Engadget.