Mass immigration of one culture into another is always going to lead to problems.
Normal immigration, on a small scale, is good however, because the culture clash remains minimal. No one is bothered by a few foreign people. It leads to ideas sharing, and information exchange. People benefit when people of other cultures are able to move about freely.
But mass immigration happens too fast, and changes stable communities too chaotically. It's very dangerous to suddenly import another culture directly on top of an existing one.
People will become extremely furious over this for obvious reasons.
The only logical path is to slow immigration to a steady trickle.
Restrict immigration only to people who've had an education, and are able to work hard at a job once they immigrate, in my opinion.
Good points. Thanks for the feedback.