So let me get this straight

What about them?

Dwayne Johnson is pretty ethnically ambiguous, and also no one saw/cared about Hercules.

I prefer established characters in American source material try to stay close to the source material. That's not to say I won't watch something like the upcoming Dark Tower movie, I will. But that doesn't mean I feel Elba was the best choice as Roland. Its no different when someone complains about any deviation from the source material.

The difference is those are established characters that people are attached to in a franchise, so any small change no matter how stupid is going to incite outrage from the nerd hoard.

What established character is Matt Damon replacing that was traditionally a chinese character?

Dwayne Johnson is ethnically ambiguous to ignorant people, this is true.

He sure isn't white. And he doesn't hide his affinity for Samoan culture.

To ignorant viewers, be they in America or anywhere else, he probably is ethnically ambiguous, much like Cliff Curtis, or any other Maori is, unless they say "Hey, I'm Maori". Because he isn't bang-on black, or bang-on white, or a fat Samoan, or obviously Asian.

It all gets very confusing and difficult for white people to label people by their ethnicity with all this intermingling, and muddying of racial groupings. And we know how important it is for white people to categorise EVERYTHING, and thereby effectively lay claim to it. If an actor is bits of something that cannot be easily determined, or cateogorised and thus determined to be 'foreign', they slide under the racial radar of these latently bigoted white folk, and can achieve success in Hollywood via their ethnic ambiguity. It just becomes too difficult to maintain prejudices in the face of so much racial complication.

Picture the mental equation of the latent racist when seeing one of those coffee coloured black girls in a magazine. You know the ones chosen so as to not offend bigoted subscribers, and appeal to black people that bought the messaging white is beautiful, but are too proud to admit it to themselves. You know like black people in an ipod ad. In their heads they quickly attempt to categorise by ethnicity to determine her worth: "Is she hot? Yes, I think she is. But she is kind of black... She obviously has some white in her too, though.... she is actually smoking hot. I'll give her the benefit of the doubt, and assume she is only 1/4 black." fap fap fap

Of course all that (except the fap fap fap bit, but possibly not) would happen at the speed of light when they sat down to watch The Rock, or Cliff Curtis pretending to be some ethnicity they weren't, or no ethnicity at all!

How the *beep* is the rock black

The tokenism is Jewish Hollywood pandering to gringos.
Enough with the pandering already!

To be fair Dances was a lot less offensive, and the Indians ended up protecting him, not the reverse.

Welcome to 2017