People don't generally like to get smacked in the face by 220+ lb. guys and have their brain slam around in their skull. Minimum wage jobs, food stamps, 40 ounce malt liquer, etc. are better options. For white or black guys.
Plus, maybe more importantly the culture is gone. We live in a culture where kids are wrapped in a protective coating from birth to adult hood (now-about 35 years old). Wear a helmet when biking, child safety seats in cars, helicopter parents supervising each and every sporting event in a kids life. Can you see the soccer moms at "boxing" practice watching 'precious' get slammed in the head, nose bloodied, and knocked to the ground???? Not hardly. This is true amongst black parents too, to a lesser extent in the ghetto but still they are much more protective then any previous generation.