Linux, Blender, and WordPress immediately spring to mind as software that would be in a very different place if their codebases reverted to public domain at the 10th year of their existence.
It also effectively turns GPL3 to GPL2 on a rolling 10 year basis.
People freaked about Tivo 20 years ago. Now imagine what kind of chaos Nvidia and Oracle could cause starting from even Ubuntu 14 or a 3.18 Kernel.
Stop promoting your faves, stop generalizing about the motivations behind your non-faves, and to paraphrase John Lennon: imagine no licensing.
Now think a little deeper how that would change the motivations of developers, massive corporations, and VCs. Especially those that have given little but lip service to the whole movement.