No, but seriously...
Flying, super-strength, ability to fly, elasticity, invisibility, etc etc. What can a new hero do that hasn't been already done?
This. We have lots of superheroes that are already great, and introducing a new one therefore faces all sorts of creative hurdles on top of budgetary ones, if we're talking movie adaptations. Hancock
was probably the biggest effort to create a "new superhero" in recent memory, it cost a ton, and its hook (a generic superhero, except he starts off a drunkard!) just wasn't enough to grab people.
Though you could make a pretty good case for Harry Potter being a "new superhero": he's got powers, a grandiose origin story, distinctive clothes, an archnemesis, sidekicks, etc. Can a brand-new new cape-wearer capture the public imagination? Not too likely, IMO, but that doesn't mean one can't tweak the formula and try elsewhere.