Why does atheist Richard Dawkins debate obscure bishops & un-credentialed YECs but even gets criticized by....?

It's a fair question. I'm guessing that Dawkins probably doesn't have enough background in philosophy to be able to hold his ground here. Ontological theism is very well developed no matter how one feels about it. Hitchens presumably doesn't mind debating Craig because he more comfortable with philosophy. I don't think Dr. Craig disputes the notion of evolution, so really I don't really see the point of having him debate a biologist.