Why would anyone do that ... I mean if you are about the music .. then music is music ... who hell cares what color your skin is .. when you sing the blues it is the story, the pain and the suffering .. that's why the call it the blues (elton john). Likewise if a black person sings Irish folk songs (I know many that do a superb job of it also)
do any of them have the need to paint their face ... makes no sense to me other than to offend and degrate

anyway .. what is the need to do that other than to offend someone I guess ... makes little sense to me ..