A little more on this: blacks often view "post racial" blacks (or even just successful blacks) as traitors "trying to be white." The backlash against Bill Cosby is the same type of thing. For a black politician to not
emphasize race as an issue puts him at risk of losing his identity and with it, the "black vote."
Yes. Same type of thing as Obama - "I'm not a black golfer, I'm just a golfer." Put people still want to put him in that box (frankly, I think the media is a big part of the problem for both Woods and Obama).
Regarding sex: its still an issue in the US, but it is fading. We probably aren't going to have a female president any time soon though. The problem is that while to a 25 or 30 year old, sex isn't an issue and young women do whatever they want, in the 60s and 70s when women's lib happened, sex was
still an issue - and those are the women who today aren't in a position where they could be president. A woman in 1965 who wanted to be a poly sci major->lawyer->politician may not have thought it realistic and instead choose to teach politics instead of being a politician. It'll be another 20 years until today's woman is in a position to run for President (and her peers to vote for her).