One thing this kind of debate always makes me wonder is just how many shades does this issue have? What I mean is a lot of people wanted Rinko Kikuchi to play this part but since we have no reason (that I know of anyways) to believe that she wanted to do the part or even tried to audition for it a few other names have been dropped and those have been mostly Chinese or Korean (or Chinese-American, Korean-American, etc.) actresses whereas Kikuchi was (according to Wikipedia) born and raised in Japan. So what I'm asking is do people think any Asian is "close enough" to play a Japanese role? There's still a fairly serious debate if the half-Indian Ben Kingsley was "Indian enough" to play Gandhi and I personally (/anecdotally) know a fair number of people who were up in arms when the African-American Morgan Freeman played the Xhosa Nelson Mandela (since, to many South Africans and probably other Africans as well, African Americans aren't "African enough" to call themselves as such because they are "too White," "too Americanized," etc.)
Obviously the bigger issue here is White casting vs. Non-White casting in Western Film-making/Hollywood rather than the issues of shades of ethnicity and nationality, but I still think it is somewhat important to look at the non-western audiences for these movies. I mean probably if Grace Park (a very talented Canadian-American-Korean actress) was cast that would probably be good, or even great for most Canadian-American-European audiences but would that be more or less controversial in Korea or Japan than Scarlet would be? Or what if someone even cast an actress who was non-white and non-East-Asian like Halle Barry? Would that be super controversial? What if it was a historically oppressed or discriminated nationality, like a White English actor playing a White Irish character or an ethnically Japanese actor playing an ethnically Chinese character?
So I guess what I'm asking in that rambling mess above is how specific to character do people want adaptations to be done? Is simply looking similar enough or do they have to be the same ethnicity, the same nationality, the same language, how precise do most people want it to be?