When we say we want to integrate other cultures and welcome them, we act like the Federation of United Planets from Star Trek: everyone from every culture is welcome to join us and enhance our and their culture with the exchange of knowledge, resources and labour. That sounds really nice, doesn't it?
Unfortunately in reality most governments are more like the evil Borg: every one from every culture is welcome to join the collective! And it won't cost them more than their freedom, their culture and their individuality.
Now, I ask you, is that nice?