The protests over gentrification that turned into brick-throwing were in Oakland. I can't imagine they'd prefer more people living there because of a short commute.
Sure but that'll take a decade, if not two. It takes forever to build these types of systems in America, especially California.
Not for the protesters. The complaint is that tech workers are driving up rents and housing prices in SF, not that they're causing traffic. (As I understand it.) If there was an office anywhere on Bart, people would even more likely to live in SF and Oakland.