“Maybe the Wayans brothers would be offensive if there were 400 years of history of whites being made to look like sub-human buffoons in American popular culture.”
So, racism is ok if someone in your linage has been a victim? By the way, not a single African-American alive today has been a slave.
So, since blacks have spent years being racist towards Asians, Asians are free to mock blacks anyway they see fit?
Your thinking is flawed.
No, however, I think it is less ok if it plays into a pattern of bigotry and discrimination. A cartoon of a scheming Japanese banker with a big nose isn't necessarily racist -- but a cartoon of a scheming Jewish banker with a big nose clearly is.
I've not seen White Chicks, but I don't see America having a long and sordid history of black comedians dressing up a white people as a means of demeaning them.