I won't get too political here.
I'll just note that many (I'm not saying ALL) of the same persons who are upset about ''white-washing'' seem very pleased every time a comic publisher, film producer, etc. does the opposite, and recasts/redraws a white character as black or brown.
And they have been known to get a bit hysterical with anybody who criticizes, even mildly, such changes to previously European/white characters.
I don't think Hollywood execs actually care that much, either way. They just cast stars they can boost ticket sales.
How many Japanese actresses are as famous in the States as Scarlett Johansen?
And are associated with a role like Black Widow, an action girl/spy?
It was an obvious pick, assuming she was available and within budget.