I largely view as the whitewashing thing a matter of marketing (though while Tilda Swinton did a great job there was really no reason for her character to be white). I mean I think of how the movie gets funded. You have a group of investors and they want to get the product out there to as many people to watch it. So they know star power so they're not going to be like "Hrm....the major is supposed to be somewhat Japanese." They're thinking "You got Scarlett Johanson?! OK, I'll invest." People that will go see GitS because they know the material is a tiny, tiny, tiny fraction of the market. The people that will say, "Hey, an action movie with Scarlett Johanson? I'll go see that."
I JJ Abrams had it right in saying that casts should reflect population. But let's be honest, JJ Abrams can coast on the brands of the movies he's making and his name. In essence, asking for no whitewashing is a bit of a circular problem. White Celebrities are put on as movie sellers because they've proven themselves in other movies. But they got the roles in those movies because they were white, etc, etc. Like I said, I think some production companies are moving in the right direction. But the cynical part of me views the problem not as a monolithic effort by people to push white culture. It's just lazy business.