No. You don't understand. It's about respecting the culture that created the story. You wouldn't expect a white person to play Pocahontas, would you?If the only reason someone doesn't like a character is because of a race, then that is, by it's very definition, racist. The person professing that opinion may not consider themselves racist, but the statement they are making is a racist statement.
/sarcasm, in case anyone was uncertain.