No matter how good our video streaming technology these days, it still makes a big, big difference to be with the right people in person.
If you were in middle-of-nowhere Nebraska you'd have a hard time finding co-founders, programmers, or investors within a 100-mile radius. Not to say it's a bad place, but it's really not the best place to be for a tech startup (unless you're completely set on a one-person startup, it's your parents' home and you just need a few months offline to churn out code on free rent and free food, or that place is your target market, in which case it might make some sense).
That said, I don't think the bay area is the only place. I'm working on an idea and I'm planning to stay in Boston for a while since the environment here is just starting to become awesome.