All I have to say is pure marketing genius. Ratings for Survivor were slipping. The producers thought of dividing along ethicity thinking that would bring them press and create a stir. Folks that might not have watched tuned in to see how this was going to be handled. Just pure marketing genius! Is it shocking? Yes! Was that the point? Yes!
That being said I haven't missed a season - so I was watching anyway.
I think that the whole premise is somewhat hokey. I also thought it interesting that the Caucasian team has mostly young people and no one who is physically unfit - the African Americans had the gentleman who was voted off (not fit), the Latin Americans have the heavy metal guy (unfit) and the Asian Americans have an older person (Cowboy.) Seems like the deck is loaded for the Caucasian team.
As for the stereotype element, I believe that it probably isn't happening as much as you would think. Of course, the producers are not editing it out. They want the shock value. As well, you are not seeing any of it in context. A key discussion before or after may have been left out.
As well, the players may have been told to say things or encouraged at any rate. To believe that some of this is not scripted is really naive.
Okay that's my two cents.