^I didn't realize he tried to write a Superman movie. Make me wonder if this isn't just frustration speaking.
As for what he actually says, I have to disagree. I don't see where any of the DC characters abilities are really that much worse than the Marvel characters. Hell, one of the next movies has a talking raccoon and a sentient tree among it's cast members. We've gotten plenty of adaptations over the last few years that have shown that the characters still work fine today. I know they've been mostly animated, but I think the things he says were true, then no versions of the characters would be popular today.