Casting the wrong race

From Twitter: GeorgeTakei: Live action of anime classic Akira will use white actors. In related news, remake of Roots to star Mel Gibson. #ShameOnWB

I think this needs to be discussed. How do you feel about race changes in classic films, comics, novels, even video games when they come (again) to the big screen? Is it modernizing for a more multicultural world or desecrating something special? Do you applaud when a member of your race gets inserted and complain if one gets removed? If so, are your motives just?

Did you cheer or groan about a black Nick Fury? Should Akira have a Japanese cast? What if the sex of the character gets changed? Are there any rules we should be following here?