How do you believe copyright is keeping the quality down in particular? As I see it, the reason is marketability and trying to conform to standards. Making a new Marvel Movie is sure to have a payoff. Making Parasite MIGHT have a higher payoff, but the risk is way higher.

Removing copyright might help to get various more spin-offs and reiterations on previous work, which does increase the scope, but taking the ability for makers to profit from their work in a traditional sense, will bring us closer (back) to a time when commissioned artwork was the main art you saw