I think I'm just getting tired of origin stories in general. These superheroes have been around and have been popular for so long that, if you don't know their backstory by now, you probably don't care to. I'd love a superhero movie that just dives right into an established world without worrying about how the heroes got started.
Spider Man already had an origin movie less than a decade ago. I don't need or want another one, even if they do things differently.