Being dark and gritty can work. Nolan did it well with the Dark Knight trilogy, and of course I did it even better with my eternally-unfinished magnum opus The Sequel, although that didn't really have any superheroes...no, scratch that, it totally did. Anyway, it's more of a risk, and it's a lot easier to make fun of when it goes terribly wrong, but I don't think it's right to be saying that superheroes should be silly as a rule. Even Man of Steel could have worked, perhaps if it had narrowed its scope a bit and focused on telling an origin story, taking its time with relatable situations and naturalistic character development, rather than quickly bolting through all that so we could see an hour's worth of mindless carnage and hilarious product placement. Bleh.