Here's another impact of free-movement; one that's been mentioned by politicians but anecdotal from my line of work.
I work with a lot of Indian programmers. It's much more efficient having some of them on-shore: I can pop round to their desks when I need to, to train them up and help when they get stuck. The company I work for just now had a policy of rotation (so one of the Indian guys came onshore for 1 year to be replaced by another).
In recent years I've lost two really bright guys that I'd trained up to be massively efficient. The first wanted to stay. He was employed via Tata and was happy to leave Tata and work directly for the company or indeed elsewhere. He couldn't stay. He returned to India and now works elsewhere. That's bad for him and the company.
The second had to leave after 1 year and still works for the company off-shore. He cannot get a visa and now the others cannot get visas either. As I've spent time with him, communication is now easy and it is efficient. However it's a loss to the UK economy. He's in his mid twenties and given the opportunity he's going to be a high-earner.
If we didn't have free movement we could choose to keep these guys here, settling, paying tax rather than two people earning, say, minimum wage washing cars in Sainsbury's car park. This is not a racist observation. I love the Poles; I have worked and lived in Poland; I speak Polish (a bit - very rusty now as I was there just after the iron curtain came down). I choose to use the car washers over the automated machines. It's an observation on the economics of the situation.
In the interests of balance, several years ago I did the same with a Bulgarian. He was a business analyst when I met him but I could see immediately he had much more potential. I spent a long time with him, training and working alongside. He's now a Project Manager and he will go on to more senior positions. He's also now a UK national. More of these please.
In the case of bright guys, they should always be welcome wherever they come from. I don't see any EU rule to stop them. Germany encourages them ( from places like India ).