I don't even think that Hillary uses identity politics significantly more than the other candidates. Outside the Lollipop Guild of Kucinich and Paul, everyone's trying to make voters feel a personal connection with them. She's just a bit more clumsy and obvious about it.
When people talk about gender and race in this election cycle, it usually gets framed as simply helping/hurting Obama and Hillary. That's not how it works. There are very few people who would absolutely never vote for a candidate because of too much melanin or too many X chromosomes (at least I'd like to think so).
But plenty of people do have biases which affect how a black or female candidate can present themselves. Essentially, they have to say "I'm black/female, but don't worry! I don't have the icky qualities you associate with swarthiness/vaginas."
It's backwards and depressing, but it's better than really overt racism and sexism. That's progress, right?