It would be a significant benefit to the people of SF if the western half of the city were significantly upzoned with a lot of new housing construction here and throughout the Bay Area, and ideally rent and house prices cut by something like half (gradually rather than in a market crash), so that more of the people necessary to run the city could afford to live here.

If by "great" you mean "where the jobs are" then I agree.

That has been the primary driving force behind urbanization since at least the industrial era.

The city is convenient and fun: it provides easier transportation, more amenities, more other people to engage with, more companies of all types to do business with, etc.

None of the jobs where I grew up were in the city (Allentown/Bethlehem/Easton, largest employers were all suburban campuses save for the electric company and some colleges. Even the hospitals were off the highway.).

All the fun stuff was in the city though, so that's where we'd go once you got a friend of driving age.

End result: cities have more fine-grained amenities. People who want more amenities live in cities.

For example, let's take a relatively common hobby of sewing. The two stores in downtown closed tens of years ago, and the only ones left are in the suburbs, unreachable without the car.

I think at this stage, the only advantage of city is bars, restaurants, and expensive clothing/jewelry. If you like something else, you are better off in suburbs with a car.

I’ve long pointed out to conversation mates IRL that for a technological civilization like ours, shelter costs are a straight deadweight, Tsiolkovsky rocket equation cost upon the innovation throughput that is the civilization’s lifeblood. In the U.S., healthcare pricing policies are as well, but that’s a different conversation. Both are stranded capital that need unlocking towards increasing the technological development pace.

But most people with mortgages are trapped like a monkey’s fist around a fruit in a jar, by the siren song of house appreciation.

I’d rather have fusion, life extension, solar system colonization, mind uploads and AGI sooner than be “rich” in real estate.

If you believe otherwise, you will learn the hard way when you seek your reforms and find that none of the people spouting the high-minded capitalist rhetoric support the actions that would bring it closer to reality. In short, the monkey's hand isn't trapped. The monkey is masturbating into the jar. It knows exactly what it is doing and you will not be thanked for interrupting.