Why has it been so long since a black band ruled rock?

Let's refresh our collective memory: Black Americans invented rock 'n' roll. So it's frustrating to contemplate the nearly total segregation among bands who have played rock music since the early '70s. OK, there have been some flies in the buttermilk here and there. Some of those flies have been as large as Prince, who endured hostility from rock fans who threw chicken parts at him when he opened… » Full Story on Salon.com