Because we have realized that national culture and not necessary colour is the issue. DNA improves with more diversity as it will chose the best combination, as a result you will see, more adaptive biologies, higher intelligences and basically superior people. The only sad thing is, the stupid and weak will find it harder and harder to get a mate. Like the evolution of the information age now we will see the class system may change to a genetic class system. check history;
military class(ancient age), monetary class (post modern), information age (modern), genetic class (future?)