And we have Asian people in the US and it'd be nice to have them take leading roles in movies and not be white washed out. Yes, this is an American adaptation, but what would have stopped it from still having an all Asian cast if they really wanted to? We have tons of movies with majority white casts and no one bats an eye.
Of course it would've been nice, and they could have casted an all Asian cast if they really wanted to.... but it's obvious they didn't want to. Hollywood is not a business built off giving leading roles to minorities out of the kindness of their hearts. It's a predominately White male dominated industry.
There's a lot of reasons Asian Americans are going to have a hard time getting leading roles in major Hollywood films. Part of the reason is there are no Asian American superstars in any artistic or entertainment medium impacting American Pop culture. This unfortunately leads to them being invisible in American media. Hollywood knows how to use superstars regardless of their race.
Asian Americans are going to have to follow the African American model and buck the system if they're ever going to see any change . Create your own films, cultivate your own audience, and ultimately you'll create your own stars and Hollywood will notice.
The other part is changing the system from within. I can put out a list of successful Asian American/Asian Western film directors and producers whose body of work consist of major Hollywood films with no Asians in leading roles, such as this film here.
I guarantee if I put out a list of successful African American/Black film directors and producers the majority of their body of work will have Blacks in leading roles in their films.
Why would a White director and producer be concerned about casting an Asian American/Western in a lead role of their movies if Asian American/Western directors and producers aren't concerned about doing it in theirs?
If anything, they reinforce this type of casting to be the right decision.