Well, babysteps and all. Do you also mind black britsh actors playing americans (e.g. Chiwetel Ejiofor in 12 Years As A Slave)?
British people and American people being lumped into the same category isn't a common issue like the 'Asian people' thing is.
Don't get me wrong, it's certainly better to break out of the 'Hollywood White' casting mentality, just rubs me the wrong way to see people calling for 'Asian actors' when Asia includes India, Hong Kong, Iraq, Korea, Thailand, China...
If you mean Japanese, just say Japanese. It does no good to consolidate people's cultural identity.
I don't have an issue with them doing a racially diverse cast, I'd certainly be interested to see Peele take the American race relations aspect to Akira with the whole 'delinquent youth' themes, there's depth to be mined there, especially with Japan's attitude toward race. It's just people specifically calling for "Asian" actors seems off to me.