Right, while when he writes the Big 'Uns On the Underoos, like the JLA, the amount he can't do with them--well, you can practically feel him chafe.
I would also add that he's still doing plenty of superhero work through Apparat/Avatar, but with characters he doesn't care about perpetuating. Which, I think, is one of the big problems with superhero comics: the need to keep these trademarks alive, dramatic arc be damned. This is one of the things I meant a few months back when I said the genre had some fatal limitations. In the case of mainstream superhero comics, one of those is actually a case of commerce and IP rights trumping art.