One of the most important provisions of copyright is expiration. When copyright expires (even if it's in 250 years), works are supposed to go into the public domain, so that anyone can use them.
Too often this does not happen. There are many, many works that legitimately are in the public domain that cannot be used properly because they are claimed as still copyrighted.
One of the biggest problems with the current copyright regime is that there are no penalties for lying, or even being careless, about what you own copyright to.
Hmmm. I wonder what I can do with that.