We constantly speak about casting choices based on their talent not ethnicity. Scarjo has proved she can carry a leading role of this significance all on her own. Given the few female protagonists being written, I would rather they gamble on a renowned actress I'm confident will knock it out of the park versus a potential unknown. Rinko Kikuchi might have been nice, but she lacks the same clout Scarjo does. Shame she wasn't considered though. It should also be noted despite its origin, Manga/Anima characters rarely look Asian. Some of the most revered series (Bleach, Fairy Tale) depict characters who look American. You even cite examples of other manga being used as reference for an American adaptation (Edge of Tomorrow, Black Swan). So I cannot see this being a risk to Scarjo's career or the Ghost in the Shell franchise, provided the writing is well done.