Now I'm insulted
Well, not actually much at all, since I live waay outside SF; this is a big place. But you see how it begins? You expressed the same stereotyped view of my part of the country that you perceived in Obama's remarks.
I understand that you came to your outrage on your own. But logically, that doesn't mean that the Republican strategists aren't delighted to see regional and cultural (small vs. large town) resentments arise in this election. They may not have influenced you, but you can be certain they're trying as hard as they possibly can to encourage divisiveness with anybody they can influence. They know from past elections that it benefits only the GOP.
In other words, the GOP benefits from anger and bitterness. Ironic in this situation, eh?