Remember that not everyone can use p2p. It makes a lot of UDP/TCP traffic, so some admins (like me) block it to prevent router hangups.
I fail to see how that matters.
If people want mp3s, and gives a rat's ass about something other than it, then let them have their MP3s.
If people want something other than mp3, like, oh I don't know, FLACs in a torrent, then why not should they have to only get mp3s?
We don't want to remove the mp3s or make them torrent only. We only want a chance to get something better than mp3. And if it's to big for conventional methods, like hosting them locally, then P2P is probably the best choice.