I had a conversation with a friend about the Joe Boxer commerical and he pointed out a similar commerical with a white man in it that had similar results:

ME: to me the ad is innocuous
ME: but many people have become hypersensitive
Friend: if I had just seen the ad without reading about the controversy....with that stupid grin he wears, I woulda thought more than anything that he looks gay...Uncle Tom and minstrals wouldn't have occurred to me....
ME: he does look gay
ME: I think that added to the offense a lot of people felt
Friend: =-O
Friend: :-P
ME: but so what
ME: what does it matter?
Friend: that's interesting...
Friend: it doesn't, not in the slightest...what I think is funny...
ME: yeah
Friend: is that some people have said that the reason people are responding to the ad is precisely because he's black....that because he's black and looking kinda dorky and silly..it makes some people subconsciously "nostalgic" for the old Jim Crow portrayels of blacks in popular culture...but that argument doesn't hold because....
ME: yes
Friend: they are forgetting about this VERY famous commercial...I think it was a McDonald's or Burger King commercial...that ran in the late '80....
ME: yeah
Friend: in which there was this brief clip..no longer than Vaughn's...that showed this fat WHITE young man doing this silly dance....
ME: uhuh
Friend: and he became FAMOUS because of that and started making personal appearances and even had his own fan club....for about 15 minutes....
ME: yes
ME: so people laugh at fat white dudes dancing too
Friend: people were responding to the joyousness and silliness of his dancing...not his skin color...so all those people saying people are responding to the boxer just cuz the dude is black are full of it...

The one problem is that the first actor was fat. It is possible that people were mocking his fatness. Still, it is evidence that the ad is not dependent on the actor's blackness.