A bit of theorising, but I think it's a bit of a "Why do we talk Goku and not Superman?" situation where, for as much flack as Smash fans get for "hating anime", there is absolutely a gravitation towards Japanese games and anime-esque aesthetics. Gravity Rush and Kat fit very well into how Westerners percieve anime - If you look at other popular Japan Studio games, a lot of them lean into the elements of Japanese culture that don't really interest otakus, like traditional mythology (Tsushima, Ico) or Anpanman/Doraemon-style kiddie characters (PaRappa, Ape Escape, Toro)