:Well for PC users this is pretty much old hat technology (having had many games in the past with either custom soundtrack support or the ability to do manual replacement of the shipped WAVs/MP3s), but the Xbox's Custom Soundtrack support is certainly widely lauded by fans everywhere you turn (probably most notably in Xbox port vs. PS2 original arguments regarding Grand Theft Auto: San Andreas). 
 :I would call it more "widely popular" rather than "revolutionary" though, as it did not really change game music in general. But if the article were to talk about how the Xbox was the first console (? I think) to support Dolby 5.1 surround sound programming thus leading to a huge increase in game music's complexity and realism (and in turn allowing enemies to be heard in the exact direction they were located in), now that technology would be far more worthy of being called "revolutionary".