Those countries just aren't ready to be allowed free movement into the UK. The whole free movement thing only works if both parties are more or less on an equal footing economically.

Now with Poland, people perhaps shouldn't panic so much, because the government really should have seen it coming that many would want to come here. The links between the UK and Poland are strong with many family already being here, historical stuff etc.
Notice how the country hasn't been flooded with Hungarians or Slovenes.
Poland is growing economically, and there's signs of a reverse in the labour flow.

Letting Romania have free access, this is worrying. The opening scene of Borat was filmed there. Ummm go youtube it. It isn't just that though, experience has now shown that there seems to be a social issue involving many Romanians here.

Bulgaria - well have many really come here? Some people I know used to worry about that, as they said Bulgaria is where the former eastern bloc used to go to recruit their "bad boys"

Maybe the real question is, just why the were they allowed into the EU in the first place? At the time of their entry, the poorest country in the EU was Ireland, which was receiving huge subsidies accordingly