The resi tower has concrete separations between floors and if you are lucky, between flats on the same floor. Office buildings don’t have any real separation between floors as you are supposed to walk on accessible fake floors and have fake ceilings too.
The sound insulation between flats on a converted office building must be nil.
A lot of the older buildings in SF just have 2x4 walls separating the apartments, with fiberglass insulation. It's not very good at insulating sound either.
If the office conversions are done properly they will be better at sound insulation than much of the existing housing stock in SF.
The real question is, why bother renting in SF when any of the surrounding cities are cheaper? Most of the reasons to live in SF (restaurants, nightlife, cultural events) are shut down indefinitely, and commute distance isn't relevant if you are working from home. Renters can get a lot more for their money in the East Bay or the Peninsula.
Because the pandemic-related shutdowns are temporary (though of course there will be lasting effects), and rents are 30% off their highs, with many landlords throwing free months and other incentives at people to get them to rent.
Sure, if you need/want to save some money over the span of the next 8-12 months, moving out might be a good idea, but if you want to live in the city, you're going to move back eventually, and moving itself isn't free. I think that's a thing that people seem to be missing: posts like yours seem to suggest that the only or main reason people live in SF is because their jobs are there and they want a short commute. That's... just not the case for many, many people.
I think there are valid arguments for leaving, valid arguments for staying, and valid arguments for moving in. But it depends on each person's individual situation and wants and needs.
There's still a fire danger, of course, with any kind of cooking, but at least there shouldn't be open flames all over the place.
So couldn’t you isolate the noise with false ceilings and walls that are constructed to minimise transmissions?
The key is the installation and design of the system, though. Miss one vent, electrical cutout, or gap (or even using the wrong length of screws) makes all that material useless.
source: I tried very hard to soundproof between floors. Sound passage is non-existent but footfalls are plainly heard.
Sheetrock (gypsum) can solve this problem if you use enough of it. But that can get expensive.