It is is an argument for selective and controlled immigration. You want people to immigrate to your country who have the education and potential to improve your country. You don't want people to immigrate to your country who simply suck down all the public welfare resources and are a net burden... as well as being terrorism risks.
Anti immigrant sentiment had to play a part. Take out the craziness at Calais and the arab migration and there is no way exit would win. But after the fact is too late.
The U.K citizens in the urban areas overwhelmingly voted to Leave. Take a look at the poll results on BBC.
Well put. How did common sense become racism? I find it fascinating that Saudi Arabia and the rich Gulf states have taken no refugees. Maybe it is more important to create an invasion of muslims into western countries than actually assist them? Mexico has a draconian immigration policy that expressly refers to maintaining its national culture. Somehow however it is totally unacceptable for us to have the same concern.