You make a very good point. Over the decades I've worked with and been friends with many true Africans—educated, Christian, articulate folks from Africa. They had nothing in common with their American "cousins". In fact they looked with contempt upon most (but not all) American "Africans".
Their opinion was not founded on race, but on a generalized debased culture which is evident in the African-American community.
It should go without saying that the ghetto thugs do not represent all African-Americans, any more than Justin Bieber or Madonna represents all white people.