Somehow "dark skinned siblings" was ambiguous enough to Shyamalan so he casted "pale fellows". Totally makes sense because, y'know, anime style is ambiguous! So that's why he made the whole thing look grey and dull huh?
"Only a few of the main characters" are still enough main characters to get wrong, and Shyamalan got them all wrong. "Fat" and "thin" are ambiguous too? *cough* Uncle Iroh *cough*
When anyone does the exact opposite of what they're expected to do, they shouldn't be surprised if people react negatively.