So, my initial thoughts were “Well, it’s because they have a goofy costume. Batman could just run around in a year one winter face mask and we probably wouldn’t question it.”
But, then I think about The Punisher, whose costume is basically a hot topic t shirt with a skull on it, and I kind of feel like his origin story IS important. That context of his dead family, ex-cop, gives his war on organized crime a lot more emotional impact. But, if we were talking some other similar vigilante made for film, maybe not?
So, maybe it’s not just the costume that makes the origin important, but the universe or medium that they exist in? We expect it from comic books or even an ordinary guy with a skull t shirt that inhabits the same New York Spider-Man and Daredevil do.