Moving from a melting pot to a stew

It always confuses me when, in Holder's recent speech for example, superficial people decry the social segregation of individuals into like-minded communities by saying that those individuals have incomparable riches to offer one another. I agree with the second sentiment, but those riches are the product of the social segregation that nurtures their unique cultural perspectives, and a project of massive integration would deprive future generations of that wealth.