i think its just a prejudice thing. when white americans and europeans hear the phrase "black man" they probably just have an image of a black rapper with a big chain and a gun. but thank god that image is dying out because gangsta rap is dying out.
that image probably also inspired black hoodlums because it was on TV all the time.
i think in 30 or 40 years this type of behaviour will die out. its not going to happen over night.