Seeing as music is a form of art, I believe that it would be AMAZING if there could be a way that people could record their original compositions and upload the audio and (optional) sheet music. As a person who enjoys composing, I believe that this would be a HUGE improvement to the site. It will help appeal to an even larger group of people who have impressive talents as well.
One of the reasons why people are against this is because of copyright violations. If they did it the same way people upload film here, then I think it should be possible.
Actually, that is exactly what I was thinking. I was going through the film deviations and I was like, why is there no audio/music category?? I suppose if someone REALLY wanted to they could upload a film them playing their music.
Well, as for the music videos so long as you credit the producer and state that you do not own nor did you create the music I do not believe that it is infringing upon copyright laws. I'm not 100% sure on that though, I should look it up.
People also do cover music and remixes and as much as they are awesome, it would be weird to not allow them or wondering they are actually made by them or having them allowed and getting closed down probably.
The only way I can see it work is screening every music submission from the few people allowed to submit music. But even then it would just be tedious for everyone.