Copyright

against -

• artist lose most of the rights to their own music
• artists need to trust audiences to fund them buy buying their music etc
• takes years to make money

for -

• the music can be listened to and shared for free
• the music can be shared amongst people which means that there is more exposure for the artist
• when using licenses that incorporate ShareAlike provision, it can be hard to monitor whether people are sharing or not
• artists can distribute without a distributor without worrying about people using their music outside its intended purpose
• no legal complications
• the music would not be protected to a  rediculous extent