I think that Hollywood has been guilty in this regard for many years. I think they have improved a great deal.
Here is a census of America by race:
White alone, percent, July 1, 2016, (V2016)(a) 76.9%
Black or African American alone, percent, July 1, 2016, (V2016)(a) 13.3%
American Indian and Alaska Native alone, percent, July 1, 2016, (V2016)(a) 1.3%
Asian alone, percent, July 1, 2016, (V2016)(a) 5.7%
Native Hawaiian and Other Pacific Islander alone, percent, July 1, 2016, (V2016)(a) 0.2%
Hispanic or Latino, percent, July 1, 2016, (V2016)(b) 17.8%https://www.census.gov/quickfacts/fact/table/US/PST045216
If we use this census then 77% of role ought to go to whites, 13 to African Americans, Etc. I am not certain that would be fair, but statistically it would be correct.
I think a lot of this is Hollywood trying to make up for their shady past in this regard. I mean they did discriminate heavily in the past with stuff like folks not getting roles and using black face which was a bad thing. A good actor is a good actor, and race really does not play a factor for me in that regard. I know Will Smith was upset a few years away but let's get real he is not the best actor or of the caliber of Morgan Freeman, or Denzel Washington in terms of acting chops.
I think the fanboys have punished movies that changed the races of major characters. Gunslinger is a good example as the latest Fantastic Four. Comic book guys are loyal movie goers but no one wants to see a beloved character changed to please others. These movies bombed. Marvel Disney has done this best and not paid a price. Nick Fury is a great example of a change that was embraced but we are talking Samuel L . Jackson who exudes cool.