I think you dramatically underestimate the place cultural differences are taking in the growing frustration of the people of Europe. Three things:
* - Because racial statistics are forbidden in Europe, whenever someone complains that element from a certain group are causing problems their opinion is immediately dismissed as being racist. If you spend even a week in Paris, chances it will be hard for you to stay neutral and support that Muslims/Gipsies aren't committing more crimes than any other groups combined.
The problem is, people aren't oblivious to what happen around them. When some of your relatives/friends gets assaulted in the subway once by someone from north-african ancestry, it is a coincidence. Twice, it was bad luck. Third, something is going on.
* - More people complain that they do not want such a steady, and large immigraiton flow. Politicians, because they are either powerless or stubborn ignore the people -> Far right politicians, who have put secure borders and immigration quota at the DNA of their programs are on the rise.
Rinse, and repeat.