It's a fact that many white musicians play ethnically African-American music like blues, jazz, hip-hop, etc. The most logical reason why they do that is out of respect for black artists, and to pay homage to them. Black music and theater has always been popular among non-whites, even dating back to the 1800's. Vaudeville performers like Eddie Cantor, Jimmy Durante, Al Jolson, Buster Keaton, and even the Three Stooges performed skits in blackface.
List of entertainers who performed in blackface - Wikipedia
This has been looked upon as being "racist" as of lately, but that's because people don't understand those artist's motivation. They were not mocking blacks, they were paying homage to them and presenting the audience with what was the most popular entertainment of that period. Just as white jazz, blues, and hip-hop musicians still do today. Just as when Stephen F. Foster wrote songs like "Camptown Races", "Massa's in de Cold, Cold Ground", "Plantation Jig", and "Old Black Joe", he was not mocking blacks. He was performing the popular culture of the day.