I think that the idea of the secret identity is more important to the core concept of certain character than others. Spider-Man, for example, wouldn’t be remotely the same series if his identity was known to the world, whereas it doesn’t much matter if the Hulk’s, or Cyclops’, is known. And I think that, for whatever reason, DC has more of these characters than Marvel. Also, in the 21st Century, with modern technology, it’s more difficult to believe that such public figures as most super heroes could keep their identities a secret. The most ridiculous moments in the Nolan Batman films are those in which Batman is involved in a car chase where he’s being pursued by the police, and manages to elude them while driving what amounts to a tank. But he needs to be able to do that, or the whole construction falls apart, so he does.