Bullcrap. Where do you think the term "whitewashing" comes from? Things like The Hunger Games, the upcoming Moses, Bane in TDKR, Into Darkness, The Last Airbender, Batman vs Superman, and so on and so forth.
If you honestly never heard anyone complaining about a ethnic character turned white, it's factual that you have not been alive for over an hour.
The problem isn't so much people don't get mad, it's just the people who get mad at whitewashing and the like aren't treated as being justified and as if our money doesn't matter. By and large, the impression is the people in charge of making these stories don't give a shit, then pass the buck on to the fans who also don't give a shit (or may be openly hostile) to absolve themselves of any type of responsibility.
To be real, I don't give a shit what trash DC fanboys have to talk about John Stewart getting play or how Marvel fanboys are going to boycott Ultimate Spider-Man because he's "just not Peter Parker." I take the very general stance of "CRY SOME MOAR" whenever that backlash inevitably starts. The problem is you got a lot of people in power who take these complaints seriously because in their mind,
those are the people they have to cater towards when making these comics.
I'm for Thor being a white woman (though I can't say I'm interested).
I'm for Miles Morales.
I'm for Sam Wilson being Captain America.
I'm for Kamala Khan being Ms. Marvel.
I'm for Robbie Reyes being Ghost Rider.
All Marvel has got to do is stop acting like black women don't exist when they make their comics and movies and they'll be so far ahead of where say, DC is, I'd be crying into my Shazam pillow because that'd be the day I'd revoke my Johnny DC card.
I'll usually go hard for these characters for what they represent: people who don't normally get the spotlight finally getting some of the spotlight.
Besides, the jury is still out on how long some of this stuff is going to last.
These dudes will likely get their toys back in a year or two and everything will be back to where it was.
...and as an aside, 9 times out of 10 the only justification required for a character being a woman of color, and/or disabled, and/or transgendered, and/or neuroatypical is "because they exist in real life." You don't need anything else.