The code names and the gaudy get-ups, for instance. Even if you're trying to keep a secret identity, an alias would be more plausible. . . unless of course you leave with no name, and the press or the police assign you one to keep track of you. The best justified one I've seen was in Wearing the Cape, where we have the circular -- no, spiral -- logic where superheroes wear gaudy costumes and have code names because that's what superheroes do. It's not quite circular because the superhero who started it took it from fictional works, in order to reduce the shock effect of powers in a world hit by a large number of disaster and the sudden outbreak of superpowers.
OTOH, many superhero novels just do it and don't bother to try to justify it -- it's just what is. That can work, too. As long as no one pays too much attention to it.
