In Wal-Mart v. Dukes, the Supreme Court set a dangerous precedent when it ruled that the women in the class action suit could not prove a common culture of sex discrimination. But sexism is no longer written in official policy. It's engrained in culture.
Immigrants would rather not be called aliens, either. Terms like 'illegal immigrant' foster a hateful climate for all immigrants and Hispanics. The term isn't just derogatory and damaging, it's imprecise and often inaccurate. Changing it isn't about political correctness, but political necessity.