Actually the initial question didn't mention the word race at all, but asked Shyamalan to "address the fan concerns about the casting" of Airbender. Shyamalan had clearly been thinking about this one because he launched into quite the talk: the overall gist of it is that the races for each group came from whoever he cast as its primary representative. Shyamalan suggests that his Aang, Noah Ringer, has a "mixed" look, so all of the Airbenders are of mixed race. His favorite Katara, Nicola Peltz, "had a lot of Russian qualities," so the water tribe became very Russian/European. And when Dev Patel was cast as Zuko, the Fire Nation was developed with an Indian and Middle Eastern look.
But the thing that really caught my eye about Shyamalan's response was the absolute first thing he said about it:
"Here's the thing. The great thing about anime is that it's ambiguous. The features of the characters are an intentional mix of all features. It's intended to be ambiguous. That is completely its point. So when we watch Katara, my oldest daughter is literally a photo double of Katara in the cartoon. So that means that Katara is Indian, correct? No that's just in our house. And her friends who watch it, they see themselves in it. And that's what's so beautiful about anime."
Naoki Urasawa's manga and anime Monster are a great example of an anime where characters' races are carefully depicted and a significant chunk of their background. A couple of us were recently talking about Black Lagoon in the office, in which the primary characters all have very specific races as a part of their backgrounds-- and almost everyone else is split into different crime syndicates based on their nationalities.
What do you guys think? Is it fair to say that "anime is ambiguous" on race, at least generally speaking?