it's basically importing in people who are highly prone to: violence; theft; vandalism; drug trafficking; prostitution; cultural seclusion; oh yeah sitting around and collecting government cheques
Strange that's the very same thing I see Poles doing in cities all over the UK. All you can do is set a criteria for allowing people into a country, if it's too permissive you'll get every man and his dog, if it's not working raise the bar.
Those "immigrant communities" are not the norm or the ideal, they're just the cheap places where the less well-to-do/less desirables can afford to live which in turn drives prices down making it more affordable to those just off the boat (chicken and egg scenario). Personally, I'm not a fan of these communities as they are insular and do not encourage integration of any sort (All nationalities are guilty of it)
Most of the Nigerians I know are from religious, two parent families and apart from some born and raised in suburbia (they have all white mates), never get into any trouble. So I always recommend, don't take you sample demographic from the hood. I walk through some parts of the UK at night and the polaks look just as likely if not more to start something than the other residents of these "immigrant communities".
I can't tell you how to fix Africa, but let's not over simplify it by saying they just want an "easy" life. Maybe an easier life, cos not getting shot by the police on the way to the shops (true story) seems like something you'd expect in any country but then not being able to find paying work when you are even willing to work in a toilet must be hard too.
Let's not forget, some on this forum left their own countries for an easy life in Poland, but cos they're EU nationals (fluke of birth) they've somehow contributed positively to Poland and the EU.... Let's not generalise too much, cos I bet for every waster of African origin you personally know, I know one that's an asset. But the only ones that make a good news story are the ones scamming, stealing or drug trafficking.