I mean the US is pretty massively stereotyped in this game too. Overwatch tends to run on a mixture of stereotypes and original character concepts. So like D'va is an original character unlike any FPS character I can think of off the top of my head, but she's also a massive reference to e-sports in South Korea.
Not sure what you're saying about homogenized asia. There's two ninjas from Japan, one of which has slightly more of a samurai style (Hanzo really can't decide if he's a shadowy assassin or an honorable warrior), a Tibetan monk who's from Nepal instead of Tibet because they want to sell the game in China and Tibet's kinda a sore spot for them, and a Korean I already talked about above. They all seem pretty heavily tied to their country of origin. The only one that I could see being a mix-up is that Mei is supposed to be Chinese but seems a little Kawaii or Moe or whatever the fuck people are calling the Japanese obsession with cuteness these days. But... Mei's character isn't really specific to any part of the world, and her fashion choices can be written off because "its the future now." We're all waifus now