steampunk costumery

Why does literally all the steampunk fashion/costumery for women that I ever see involve corsets in some way? I mean, your character is smart enough to be able to invent some sort of hydro-electric plasma gun out of scrap copper from a grandfather clock, but she doesn’t understand that she’ll be able to breathe a lot better and not pass the fuck out while running around shooting it at sky pirates if she wears something a little more practical?