I think you have it backwards; 'gangsta culture' is caused by and is in reaction to the continued exclusion-by-other-means. "If you won't let me into your circle, I'll make my own circle ..."
[WS:] I am pretty sure that if you get enough members of the chattering class, you can spin it any way you want to avoid any serious analysis.
So do you really think that the fact that kids dropping out of schools like flies has no effect on their earning prospect, or you are just trying to guard the received wisdom from the reality check?
BTW, the idea of "acting black" that I just floated come not from my imagination but from schoolteachers, whom I know a few. I value their word - more so than that of spin meisters - because these folk have direct empirical everyday experience of the phenomenon in question, they really care about the kids they are trying to teach, and they tend to be level headed, telling what they see instead of having an ideological score to settle.
In any case, if you believe that this something that is "hard to see" (in your own words) as opposed to what most normal people see in plain view, I am pretty sure that no empirical argument, let also my humble conjectures, will sway your article of faith.
Wojtek