I’m speaking of creative works in particular. I’m generally in favor of the media entering the public domain when the artist dies, but when something enters the public decay, shit gets weird. Having Spongebob as IP keeps him on rails for who he is as a character. Change that, Spongebob as a character is changed by the public that could make the original unrecognizable. What’s the line when a derivative work becomes it’s own IP? What do you think?
Having ip doesn’t project your character from being distorted by the public in ways you don’t expect. Similarly, not having ip doesn’t mean that the character is now completely out of your control. Others have provided examples such as Sherlock Holmes and Shakespeare where the characters are in the public domain but still keep their original meanings despite being changed by fans.