I find it amazingly obnoxious that, here in the USA, we keep pretending like all asians are interchangable. Apparently, "they all look alike to us?" Sulu's background was always intended to be Japanese... Takei is Japanese... and (and I've pointed this out before) there's a strong dislike for Koreans among Japanese and a strong dislike for Japanese among Koreans.
Go to Korea or Japan and ask someone about this, and you'll get the same response that you'd get if you did "roots" with a bunch of white men wearing black-face.
Pegg is the first real casting decision I've seen that I find deeply worrying, though. I get Cho... he's asian and the production staff are simply showing a bit of ignorance there... nothing intentional and thus nothing worrying about their philosophy.
See, Pegg is an entertaining actor... I've seen him in a lot of things and I've enjoyed his work... but he wasn't the best choice for the role. He has the one major advantage, however, of having worked with Abrams before.
That seems to be a trend. Abrams is building a project, not around who's necessarily the best choice for the role, but who Abrams knows and personally likes. Pegg has worked with Abrams before (MI-3). And I see his casting as an example of "I want to put my pal Simon into this flick because I like the guy."
As for Pine, I can see him in the role. Having finally heard a clip of his voice, I can HEAR him in the role. I'm in a minority, it seems, in thinking that Urban can carry off McCoy well. Quinto DEFINITELY looks the part more than any other actor I've seen or heard of (his voice is a bit jarring relative to Nimoy's though). The new Chekov is OK (but I wish they'd actually cast a Russian actor... as opposed to an American actor of Russian descent). Seldana looks the part, but I wish they'd cast an African actress... ah, well...
The only ones who particular bug me are Cho (ethnicity, not talent) and Pegg (just not a good fit).
Neither of those is going to ruin the film for me... but both indicate a mindset among the production crew that, if applied elsewhere, COULD ruin the film for everyone.