As economic power concentrates in parts of the world and declines in others, it is only natural that citizens seek to move to a place where a better life is more likely. While industrialized, modern nations like the UK and the US are not battling well against the free market, citizens seek to move there because of the guise of freedom and opportunity.
The UK might not be the freest country on earth, but if people wish to move there, so be it. However, today, people seek to make their little piece of Earth exclusive to somehow entertain their egos and to somehow justify to themselves that living on a piece of land north of a border will make you a better person. I am an anarchist, so I support the abolition of the state, and with that cuts out borders as well. To block someone from crossing a line because you fear it will block you from taking an opportunity on your side is ridiculous. It is only another regulation in the free market, as you are preventing competition from being public.