Obama didn't emphasize his race because less than 15% of the US population is black, and there's a long history of other black candidates and activists who are

Obama didn't emphasize his race because less than 15% of the US population is black, and there's a long history of other black candidates and activists who are almost viscerally repellent to the mainstream (Jesse Jackson, Al Sharpton, Malcolm X etc). In particular Obama didn't want to fall into the "angry black man" stereotype. I don't think it's a good idea for Clinton to play up the woman angle, but at least she's targeting a much larger demographic encompassing half the population. Also, identity politics has a long history in the Democratic party. And for what it's worth Trump has used identity politics to his advantage on the Republican side.