You have really hit the crux of the issue. We shouldn't allow corporations or individuals to control something that has become part of our shared culture. Beyond shortening copyright lengths to the absolute minimum required for the statet purpose of encouraging more creation we probably also need limitations on author rights for works that have gained widespread public adoption similar to how trademarks can become genericised. At some point you shouldn't get to decide if and how your creation is distributed even if you can still demand royalties for a while.
