I heard an interview with one of the producers. According to him, it was a response (a sort of "throwing up of the hands") to all the complaints they get every year, year after year, that, one way or another, they have always skewed the contest racially. They figgered, "what the hell, if we're going to get accused of it year after year when it's NOT our intent, let's just have a truly race-based contest".

that's how I heard it anyway.