Generally, all art is derivative one way or another. Many artists don't want to admit it but their work is often the product of the times and they drew inspirat

Generally, all art is derivative one way or another. Many artists don't want to admit it but their work is often the product of the times and they drew inspiration from existing work. This is what underlies "Great artists steal". People can use great art from the past to create even better art. For example, much of modern media borrows heavily from mythology to help them build intriguing fictional worlds. If creators had a stranglehold on every single idea they produced, art would have advanced at a much slower pace. Allowing derivative works would lower the barrier of creating great work, much like open source helps software solve people's problems. Mickey Mouse's copyright expiry allows people to create characters that look like Mickey Mouse without getting sued. I'm not sure how important that itself is (given I'm no fan), but I see no reason why it should be granted an exception.