> What reason is there to believe that the same driver who would run a red light (by accident or otherwise) would generally make better ad-hoc judgments without the light?

There would still be assholes. The difference is the other drivers would be checking for cross traffic instead of going as soon as they see the green light.

I'm certainly not convinced and in particular doubt you'd get high traffic flow, but it seems quite plausible for less busy intersections.