I have complained about this topic before.
Back in 1967, an episode of Star Trek featured as its villain, a genetically engineered superman named Kahn. The creative team took the unusual step of imagining this character as a Sikh rather than the usual stereotypical Aryan Übermensch. Then, in what was in its time a strangely courageous move, cast an ethnic actor, the late Ricardo Montalbán in the part. Fifteen years later, Montalbán reprised his role in the film Star Trek II: The Wrath of Kahn. His iconic performance as the superhuman and strangely sympathetic mastermind assurred that the character would be remembered as one of the greatest movie villains of all time.
Decades later, in the supposedly post-racial era of an African-American President, Kahn makes a re-appearance, this time played by Benedict Cumberbatch, an English actor so WASPish that his very name drips with Rugby School and cricket bats. It is as if, after all this time, there are still too many in Hollywood who cannot accept the idea of a genetically superior man being played by anything other than a white actor of Northern European extraction. Even if this is the not the case, it still begs the question of whether or not we have really made any progress after all these years.