It gets even more complicated if you have a spouse/partner that also works. Lots of 2-professional families will never leave a huge metro, even if one of both of them could find better work in a different (but not the same different) city.
We have compromised by living in the middle, but we both need to commute for about 30-40 minutes to our respective work places. I view this as an investment in our future. Right now we are both building careers which will make us much more money in the long run than the cost of commuting.
Coverage is also really poor, especially in the southern areas (Cupertino, Campbell, etc.)
(Just to clarify: Biking in the Bay Area is really good. Public transit, at least in the South Bay, not so much.)