There's little doubt that UK has become a fertile ground for migrant harassment. Whether this is happening now more in the light of the Brexit or it's simply being reported more as a reaction to the "Leave" aggressive campaign, it's unclear.
But this article by a right-wing Romanian blogger makes a simple statement: when a migrant leaves their home choosing a more civilised country to work in, they take their habits along and thus degrade the better environment which they choose to live in, alienating locals.
I like the formulation of the idea, because if you spend enough time with people who dislike migrants, you will find that their complaints do come down to simple issues. In here I will try to list some, along with my own thoughts, starting with the above.
Migrants bring along their "uncivilised" habits. tainting the local environment: civilisation is simply a pattern of habits found to achieve positive results. Don't litter. Be respectful of those around. Live and let live. Don't smoke in enclosed spaces. These are patterns found beneficial in some countries, but not in others. Ask anyone and they will name countries they are most familiar with as displaying habits they consider civilised. Anyone moving abroad will become, to some extent, an 'uncivilised' nuisance. Whether you're a westerner moving to the east or the other way around, the greater the distance the greater the perceived civilisation gap. I'm sure that people love the comfort of these small 'take them for granted' behaviours, but even within the same geographical area not everyone will abide by the same conventions. In Germany I've seen native Germans behaving more uncivilised (as per local customs) than any migrant. Civilisation is just a label and a label than can be temporarily suspended in order to have fun or simply to interact with others - these interactions and the discovery they provide are key to cultural exchange and progress (sorry for the deep left-wing tenet, though).
Migrants don't adapt and don't learn to communicate. Let's be clear here - people don't adapt. They hang on to their habits, their ways of doing things and will always look for familiarity in some area of daily life while experimenting in others. An American in Abu Dhabi won't readily adopt the Emirati way of life. Likewise, an Emirati won't become European when migrating.
Communication is another matter though. Communication is quite essential in order to benefit from cultural exchanges. Not learning the language can lead to alienation for the lone migrant and to forming small foreign communities of same-language speakers. These communities are virtually enclaves, minorities with limited-to-no democratic representation. Without significant cultural exchange, alienation is just about all that can be expected.
Migrants come to reap the benefits of the world we've built. This is the right-wing view at its best. We've been born here, our forefathers contributed their time, tax money and so on to building everything (from services to infrastructure) that makes this place a great location to live in. They want to benefit from this without having contributed. We've built something better than them, but it's ours - we are all not equal and they need to accept that.
Nationalism is the core of the right-wing and what makes the future of the UK scary, because this what's taking over. And in its statement, it's a legitimate view. Throughout history we've built something and we don't want to share it. Of course, closing down does have consequences and in today's connected world isolationism is a bad policy.
Cultural and economic exchanges are a reality, this means people need to communicate and to move around as needed. Using the benefits of a better system to get started is just an investment in the future of those migrants so that they will be able to contribute back. Sure, some may try to abuse the system but then again abusers are also found locally.
There's no perfect system, really, but if anything like adaptation is needed, then it's needed on a higher level. We need to adapt to a much smaller world, where people can easily travel anytime and anywhere.
Where communication channels are shorter and shorter, nationalism has no place, even though cultural preservation is a noble goal. If you look at the map you will see that it doesn't reflect reality anymore. Lebanon is not next to Romania on the map, but to cross the border all I need is to pass the boarding gate at Bucharest "Henri Coanda" Airport. We are all neighbours now.