I can't see where (in those articles) it is stated that the drug dealer was here legally, nor where it says that the Nigerians entered the country illegally.
Even if the above assumptions are true, plenty of illegal immigrants who don't seem to want to work or integrate seem to be allowed to stay - so why kick out those that seem to be working with society rather than against it?
If you are allowed to be here legally and you continue to live in a law abiding manner then that's fine, if you aren't here legally or you start breaking laws then you should be deported, simple.
My wife is Mexican and we went through an awful lot of red tape to be in the UK legally, to see anyone trying to stay illegally, taking it for granted or milking the system infuriates me.
Someone going to court claiming victimisation of being black/lesbian/gay seems to be an increasing theme. I wonder how long it will take before a white straight person goes to court claiming discrimination.