Those groups are what have made the British people, and the key also being that they are closer in a lot of ways. We had formed a monotone culture pretty much. White British people have become a minority in their own capital city in a matter of decades. That's insane. These policies have been carried out with evil intent and we're seeing the results more and more frequently now.
I think that you are right in what you said about monotone culture to an extent. I think a better word is assimilation. It ought not be a lofty ideal, it ought to be a requirement.
I am certain that there are many people in Britain, America and Australia who want ALL Muslims to stay away and all people from other cultures. Most don't though. I believe that most are happy for the variety and diversity BUT they want the immigrants to make their host nation their new home. Home in not just the residency sense but the abstract sense. The pride and patriotism.
I am a mongrel. I am part Irish, part English, part German and part Aboriginal. But I am 100% Australian. Do I feel the longing to embrace my Aboriginal culture? My German? My Irish? My English?
No I am Australian. I grew up with a diversity of cultures. I knocked around with Yugoslavians, Italians and Asians as a boy and in my early teens. I was Very close as a late teen and early 20's with Indian and Greeks. My First real love was an Egyptian girl. As I was working I became close to a lot of people from different Muslim persuasion too. All of these people were 100% Aussie too BUT they celebrated different occasions to me, they had different and exotic food and some of their beliefs were slightly different.
But each of these people assimilated and loved Australia. Some were first generation and some second and some third. This is where the problem lays with Radicalised Muslim extremism. It is not like people that I mentioned above. The radical Muslim extremist sees immigration as a religious passage of hijrah. It is not to make a home but as part of a greater effort to dominate and colonise. Letting these people in is not to soften their hateful resolve or to give them a new point of view. These radicals are toxic. Their resolve is absolutist and nihilistic. They not only do not understand the need and expectation to assimilate, they are completely uninterested in such a prospect.
As long as governments pander to the concept that stating these things is bad, wicked, fear-mongering and bigoted, then these nations will be hurt continually and the citizens of the countries will bear the brunt of the extremist inclinations.