My guess is that white English people were able to listen to black American music and emulate/appreciate it freely without the anxieties present here in America over race relations. And this goes back to the Rolling Stones internalizing blues or David Bowie singing soul all the way to the Adele/Winehouse/Jess Glynne types all over the radio in recent years. A white girl from Wales or whatever doesn't feel weird attempting to sing like Aretha Franklin or Mary J. Blige, but someone in Tennessee feels an invisible barrier there, as if she's acting in someone else's role. Likewise, Hendrix aside, the reason why so few contemporary rock musicians (or country, etc.) are black has to do with self-imposed notions about what music one's group possesses. I still remember when nikkas would sit down at the school dance when Smashmouth or something came on, and white people would jump up enthusiastically. 
It holds water. 
