I think anyone who moves especially such a long distance would be affected by the welfare. It causes a strain on the family and on money because it isn't a cheap or easy thing to do. There should be ways to make long moves like that easier on people who really want it.
The Roma who come to Germany and the UK from Central Europe are highly attracted by social welfare programs. The Roma, or gypsies, as they are most commonly known, tend to be drifters and criminals and highly insular, holding no allegiance but to themselves. Traveling to new countries just to get covered by welfare programs is a problem Europe cannot afford to tolerate.
Because the UK and Germany are doing relatively well in comparison, they are able to run more social programs such as social welfare benefits. Of course this attracts people. Particularly people who need these services. While the services are designed to promote the country, people will take advantage of any resource they can. This expands beyond just the poor though. Citizens who are doing well may move to a different country just to have that bit of security. Knowledge that although you are doing well now, you may not be later and the safety net keeps you from starving is a big motivator.
The Roma who move around Europe are certainly going to look for the best places to settle, as would anyone who was an immigrant. The rules should set boundaries and then follow them but should not discriminate against the se people who are just following a long and age old tradition.
Seriously, what is with the race problem in the Lowlands, always stereotyping other races, like WTF? No, the Gypsies were persecuted in many countries in Europe. Many have no homeland. I think it's messed up that people believe this crap. Seriously, typical Lowlanders stereotyping others. It's hysterical to be honest.
I don't think welfare is the main thing drawing so many central European Roma to Germany and the UK. I believe that they had no jobs and no chance to make better lives for themselves and their families, so they made decisions to emigrate. I believe they would like to find a place where they can work, be accepted to some extent, and make it their home.