I expect it is also at least four times easier to raise capital in the Bay Area as it would in most other cities in America. These things have a way of evening out.
Most of the interesting startups I've seen recently have a small office in the Bay Area to go with a preference for real operations in other cities. Probably an efficient way to raise money from VCs who apparently think Google maps is the tool for investments and yet not have to excrete rainbows to reach profitability.
EDIT: I shouldn't say "the Bay", but rather, "the Bay/LA/NYC/Seattle". I more mean "top tier startups cities" rather than strictly just the Bay, per se.