Just in time for the Oscars, the genius team at Last Week Tonight with John Oliver basically just dropped the most definitive video about why the Academy Awards are so white. From now on, anyone who brings this issue up will now need to just refer to this Oliver bit as the gold standard. Watch and enjoy.
Answer to the titular question:
"This" is still a thing because Hollow-Wood is not the place to go to for intelligence, social conscience or historical accuracy.
It IS the place to go to for the continuation of stereo-types, negatively-attributed "qualities" like being "articulate" (for blacks), being a hard-worker for Mexicans in lettuce fields or the place to go to for media cartoons that re-assure the majority of English-speaking, white America that all will be well as long as 16 y/o blonde shiksas are getting off the busses at the Greyhound bus depot in Hollywood to star in movies for guys with names that end in "berg", "witz", "ski" , "feld" and "ner".
"It" will always be a "thing" in a place where mediocrity, political cowardice and the fastest path to a quick buck is priority number one.
And if you want to see what political correctness and cowardice REALLY look like, just tune-in on the new SUPERGIRL series on TV...in it, "Jimmy Olson" who was the proto-type of white nerd in the 50s is NOW a buffed black guy with a penchant for an idiot blonde in a cape.