Actually most of them have been dead for a long time so it wouldn't really matter, but I agree with you some things should not be patentable.

On the other hand imagine a world without patents and you'd probably get a world fill with trade secrets and that is even worse, at least a patent guarantees that the idea will pass to the public domain after a certain period. Would the world benefit if technology was segmented and kept secret like the coca-cola formula?

But seriously that is a great discussion for different thread.

At least patents are only 20 years, copyright is forever.

Copyright isn't forever. It originally expired 17 years after the death of the author. Unfortunately Disney pushed for extension of copyrights every time their key copyrights (Micky mouse & friends) were about to expire and have been able to push extending them quite unreasonably.

Right, Disney has effectively made copyright forever by making it last more than a lifetime.