I agree with copyright in a sense that people should have a chance to profit from their ideas before it gets stolen, but you are right that it is way too long of a term. It stymies creativity when people can milk the same idea for many decades.

I would think for creative license like an idea for a cartoon or comic, 10-20 years is more than enough. Then they should try and make new characters or start competing with others trying to improve the character.