Ignoring the fact that the GPL doesn't have anything to do with software patents, ignoring the fact that this analogy is wrong, let's pretend for a second that it does make sense.
If you went to someone like Stallman and asked him "you can have the GPL, or we can get rid of software copyright", he would not choose to keep the GPL. The GPL is a stopgap that we use to keep some software free in a world where software is not free by default.
But we currently like in a world where snippets are fair use. Taking your analogy at face value, you're talking about getting rid of our freedom so we could have a limited scenario where we can claw a little bit of it back? Some kind of snippet GPL?
So it still doesn't make any sense. Even those most charitable interpretation is still a bad trade for us to make.
We have the GPL instead of trade secrets, we can actually see the code without signing away our firstborn.
I don't see a down side here.