And many content creators might benefit from an expanded public domain, or they might not... There's already tons of creators, they seem to be getting by? Well, actually, some are getting by and most are probably hobbyists or underwater much like most arts. I'm not sure expanded quantities of available characters would necessarily change much.
I would suggest that artists who say they're producing fully original works are just poorly educated in art history. Making something that has no prior influences would be extraordinary in the modern world.
Also, the entities most capable of exploiting long copyright terms are corporations. Individuals simply don't have the resources to keep something relevant decade after decade save for a very small handful of exceptions like J.R.R. Tolkien.
I also think you're missing my point a bit. Just cause you study lots of works and create an original creation which borrows influences isn't the same thing as requiring use of a copyrighted piece of work.
It's pretty silly to suggest I was implying artists have no influences cause I classified works without any copyrighted material as original.
My point was more... just cause a bunch of copyrighted work becomes available does not necessarily imply creators and artists lives will be substantially different or better off.