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.