There hasn't been a black wrestler that can pull the numbers. The Rock did so well because of his personality and how he was portrayed. Booker was another but he didn't have long lasting style or persona.
The WWE is an industry which thrives off its audience (largely white) of rednecks from south America and the chavs of the known world.
Unless there is a monkey doing good party tricks, they wouldn't be liking it. Times are changing nowso who knows what may come in the future. Maybe a thread about there being no Chinese WWE champion.