: 2) The mixing they have to do with dialog would get screwed up if they
: allowed people to talk while custom soundtracks are playing.

Not everyone needs to hear the same halo songs over and over. After playing through the campaign 5-6 times, and endless games of firefight... I like to listen to my own music. The warning is there to warn you incase you haven't played through yet, which is fine. I would hate if they prevented you from listening to your own sound tracks.

... and I disagree. The custom soundtracks they have for the 360 are a step up from the Xbox 1. I hated how some games prevented me from listening to my music.