Why not simply remove the ability to sell the patent to someone else? Sunset the validity of the patent like the original scope of copyright, and limit the tra

Why not simply remove the ability to sell the patent to someone else? Sunset the validity of the patent like the original scope of copyright, and limit the transferral to being able to license it for use so that the only financial benefit goes to the original R&D crowd. That way it still promotes research but limits the possibility of patent trolls since they'd have to actually do the research themselves.