I've meet many artists here and I agree that changing the approach of letting them choose the licence may work to get higher quality, but also let's be honest a $8 upvote is not so motivating to work in a piece for more than 2 hours; @slothicorn's VP needs to be taken more seriously and don't let it be below 80% and allow it to recharge to at least 96% before voting again.
Also I am thinking there is need of proof of work, to make sure it is not plagiarisim, I started asking people to make sure, but then i realized i could get enemies :s and flags x.x !... Proof of work would solve a half of the problem; an account like "slothie-police" could help too, to check and ask in posts in doubt to prevent mistakes before the vote.
Finally, a team to decide the % upvote would decrease taste subectivity.
I think that would encourage artists to join.