It's stupid casting. Why not have Depp play the Lone Ranger and get an actual Native American to play Tonto?
So people might get up in arms about a White guy playing a Native American role, yet everyone thinks its fine for Laurence Fishburne to play a White role? Hmmm...
You really don't see the difference between allowing a minority to play a character that's commonly white (but doesn't have to be white) and letting a white man play a character that's very much established as being of a race that's pretty much a super-minority?
There's a world of difference between these two situations.
Bingo.
Tonto's Indian heritage is an essential part of his character. Perry White is a hard-driving newsman; his race has nothing to do with the essence of his character. Unless you're doing a 1930's period piece, there's no reason he has to be white.
Plus, of course, white actors have way more opportunities than Native American actors, so a white actor claiming one of the few roles specifically intended for a Native American actor is a much bigger deal than a Native American actor taking one of the five million roles that could be played by a white actor . . . .
There's no equivalency here.