A lot of artists are much more concerned about how their work is used and how it's disseminated. That, to artists, is as important as the money, for some people. ↗
There is no sense in owning the copyright unless you are going to use it. I don't think anyone wants to hold all of this stuff in a vault and not let anybody have it. It's only worth something once it's popular. ↗
The marketplace can handle this. The laws are there. The courts have shown a consistent ability to find a balance between copyright owners and copyright users. ↗