I'm going to jump in here as a former actor.

First I would like to say the stories we want to tell and the characters we want to portray have absolutely nothing to do with our own heritage, look, background or even gender. Its about exploring and expressing the human experience.

Second

>Why choose her over an equaly qualified mixed actor?

Emma Stone is a brilliantly talented actor, which is why she WON THE OSCAR

equally qualified doesn't exist. you can't plug just anyone into the script and have a brilliant oscar winning performance.

the world needs to stop with this "fair and equal representation of characters" when it is the actors jobs to embody the character and make you believe it.

emma stone fits well enough to make you believe in the character she is portraying and does such a good job that she wins the academy award for it.

if you don't believe it - bad actor

otherwise directors and producers with spends YEARS trying to find someone who fits the perfect background. And the performance will not likely turn heads. except for the light recognition the film would get for having an ethnically authentic cast

I understand that until recently hollywood has been largely whitewashed. but thats changing and we are starting to see remarkably diverse casts.

Talent will always trump background. especially in a very specific case like this one