So I decided to do something about it and I'm urging everyone who is as bothered about this as I am to do the same:
1, Letters to Paramount. (Here's a guide on how to do it properly.) Let them know that the institutionalized racism brought about the re-casting of "21" and "EarthSea" is no longer an acceptable way to do business.
2, Letters to the Media. ) Here's a list of email addresses. i09.com has picked up the story so yes, this does work.
3, Most importantly: Keep your money in your pocket. Yes and that means: "no watching it for the lulz." Actions always speak louder than words. Yes, by then it will be too late to change the casting - but hopefully, it will just be in time to stop the sequels. But most importantly, Hollywood might - just might - begin to understand that the commercial "advantage" of casting White people to play Asian roles in an Asian fantasy might just be over-weighed by the fact that no one will come to watch that movie.