Hollywood has this thing where they believe that if the star actor isn't White the film will flop. The director of Independence Day had to fight tooth and nail with the Studio to cast Will Smith as the lead. To their great surprise the movie was a commercial success.
Most of the time when characters have their ethnicity changed to White by (modern)Hollywood, it was in a story where their ethnic identity is not a central part of their character. I mean honestly. Making Goku White or Aang White isn't the same as having an all White female cast for the Joy-Luck Club. Or having White guys play The Five Heart Beats. Most of the time when (modern) Hollywood White-washes a character it's in an instance where their ethnicity is not salient to them.
So why does it piss people off? Two reasons. The first is because minorities don't get a lot of chances to shine in Hollywood movies, and people don't like seeing the already sparse roles being taken away. Most of the time people who say it's not a big issue, don't understand the full implications and affects of an ethnic group not being portrayed in the media positively. The second reason is that (modern)Hollywood rarely if ever take a classically White character and replace them with a non-White. Off the top of my head, I can think of three instances, and two of them are Marvel movies.
Anyways, long story short...Hollywood Studio execs feel that being as reductive as possible will always bring in the most revenue. It's not going to change anytime soon. Until the revolution takes place, there are plenty of great Indie movies worth supporting.