Precedent for highrises
The Aaron Betsky proposal isn't so out of the ordinary for San Francisco. The SF Chronicle just had an article yesterday about Park Merced which houses some 7,000 people (or 1% of San Francisco's population).
...one of the biggest apartment developments west of the Mississippi, complete with 11 13-story towers and 1,800 townhouses spread across 144 acres just south of San Francisco State University. Built by Metropolitan Life Insurance in the late 40s, the development was one of several large-scale communities aimed at creating starter homes for returning World War II veterans
I had no idea Park Merced even existed. So we have a precedent. The fact is, if we're going to make San Francisco attractive to nonprofits and technology startups, housing costs must be brought under control.