If you need to significantly lower your quality of life just to work in a cool place, you seriously need to rethink your life plans.
By the time you'd get to the expense of owning a car, I presume a lot of other luxury expense would've been dispensed. Therefore, it's logical to assume you'd get a lower quality of life as a result.
If lacking a car, you find yourself walking more, aren't you healthier? Doesnt San Fran have among the greatest selection of fresh foods in the country?
We can go on, but clearly cutting expenses doesn't necessarily mean a lower quality of life.
You pay a premium for reduction in economic risk and a desirable lifestyle. The fact that younger generations overall have a lower standard of living due to baby boomers and fiscal policy decisions doesn't mean they are irresponsible.
Also, contrary to your assumptions, I find my "quality of life" has dramatically increased since getting rid of a car due to not needing to stress out in traffic (and dodging cyclists); not doing any car maintenance ever; never needing to look for parking and the unknown time duration that could require.
As far as not having a car: I grew up in Los Angeles and I can tell you that the ~10 years I've spent living without a car in SF is a trillion times better, in almost every way. Even leaving the absurd expense aside, the hassle of having a 2-ton ball and chain that needs to be fueled, parked, maintained, and moved around with you everywhere you go is not even close to worth the advantages, particularly when you can rent a car as needed and still end up paying tons less. It's hard to oversell the relative freedom of being able to make plans on the fly with friends all over the city while rarely having to figure out the logistics of how you're gonna get around and how to fit your car into your plans. Having spent a lot of time in both living situations, I'm close to the point where I consider every non-discretionary mile traveled in a car to be a failing of transit policy. And I actually enjoy driving! I just get my fill of it once every month or two when I happen to be on an excursion with friends where I'm the one driving, and being required to do so (and required to own a car) is ridiculous. On top of that, the fact that my transpo budget is almost nil means that I get to rent as nice a car as I feel like and don't have to think about whether it's "practical" to own.
Regarding roommates, this doesn't appear to be a Bay thing as much as a "dense city" thing. My take on it was always that if I'm spending enough time in my apartment that having a roommate is annoying, I'm probably living in a boring-ass city. So far, this has held up pretty damn well: I spend only a couple waking hours in my apartment each day, and I enjoy the company of my roommate quite a bit in this hours (for example, we often cook together). I readily admit that this is a preference thing and it's just as legitimate that some people are considerably more couch-and-television-bound, but it's sort of bizarre to claim that that's objectively a "lower quality of life".
As far as keeping track of expenses, I have something like an 80% savings rate and I still keep a casual eye on my discretionary expenses. How is being aware of your expenses a lower quality of life?