The "step" thing in that particular genre of porn is there for a legal reason, as recording that sort of content is illegal, but in truth it's meant to simulate a real relationship. I blame people who grew up with divorced parents.
The bit about surgeries is done because porn producers don't like girls who just do a couple of videos and then bail out. Getting surgeries is like a way of telling them they're for real doing this as a career, and plan to stay for like 5 years or so.
Cosplay porn in the west has too much of that "i'm wearing a yellow bikini, that means I'm Pikachu!" thing. In Japan girls stay in costume through the entire video, but you have to put out with their goddamn squeals, censorship doesn't bother me in this case since the outfit is the focus.
Btw asian girls in asian porn squeal a lot because asian men like it that way. Of course that moaning isn't natural and asian women moan like just any other adult woman when they have sex. But the prospect of them being sexually mature scares asian men apparently.