It is an attractive location for young people that want to live in SF instead of the boring burbs. Downtown has a ton of food options for lunch. You can walk over to a Giants game or to the waterfront. Union Square in particular has turned into something of a trash heap, but FiDi to the north and SOMA to the south are (mostly) attractive.

It is easily accessible for anyone on BART or Muni lines so you may not need to own a car.

Outside of that, it's still a flex to have a downtown SF office. This isn't just for warm feelings, it can affect fundraising and talent attraction.

And currently, office prices are super low in SF. My company is paying about 1/5th of the price (literally) for the top floor of a building compared to a company that rents the floor below them (which signed a 5 year lease in 2019).