It's not that he dislikes steampunk. He's enjoyed some of the books. He doesn't "find anything intrinsically wrong" with the aesthetics,
as long as steampunk is nothing more than what happens when goths discover brown. Viewed as a fashion trend for corsets and top hats, steampunk is no more harmful than a fad for Che Guevara tee shirts, or burkas, or swastikas; just another fashion trend riffing thoughtlessly off stuff that went away for a reason (at least in the developed world).
Because you see, if you spend a minute or so thinking about it, steampunk takes place in a period in time when horrible things were done to large numbers of people, as a matter of course. There was nothing romantic or lovely about it. And there's something just a little bit creepy about making it so.
Not to mention that this particular branch of science fiction is kind of lacking on the "science" side. . .
But don't read what I have to say. The rant is much better.