Imagine how much better the world would be if the copyright term was shorter and/or if past a certain point, registration (and payment of fee) was needed to renew copyright and use the full term.

Imagine all the incredible fan works that could spark careers and businesses if e.g. the original star wars trilogy were public domain, or how many indie dev studios could get started by riffing on pokemon. But alas, fans of both franchises continue to make works but can't profit from them and need to pray that Disney and Nintendo won't send lawyers after them if they get popular

“Or” would be terrible. Every work that’s particularly interesting would just be kept in copyright forever by the estate or corporate overlords.