Jerry - this has been proposed from time to time, but there are a lot of reasons that (IMO) it should not be done. First and foremost, the very people whose public trees you (rightfully) despise would be allowed to have an opinion on the propriety of YOUR tree - and if ten trees say X (incorrectly) and only yours says Y (correctly), then the consensus is likely to be that YOUR tree is the one that's wrong. That is, the votes are going to be for the ten that say X, because "everybody" says that, so you are the one who is out of step, and therefore "wrong" (never mind that the others all copied mindlessly from each other, and that even if those trees have a few records or photos attached, there is a high likelihood that they attached anything with a similar name, without regard to all the indicators that point to it not being the same person).
I agree with the comment above - I would remove/privatize my trees immediately, if such a system were put into place. Also, I would not want to take time away from my own research just to try to critique the messes other people have created.