I don't see what is so wrong with gentrification. As the economy expands and people become more prosperous, it restores blighted parts of the city to their full potential. I also think that rent control is disrespectful to the rights of the property owner. Other than making sure that there is no discrimination, and that properties aren't fire traps, government should get out of the way.
What you typically see is long-time neighborhood residents being displaced by wealthier newcomers. In a poor neighborhood, this means that people who are already vulnerable, especially those that are renting also have to cope with a whole new set of problems -- landlords who desperately want to evict them, cost-of-living increases, increased pressure from law enforcement.
The Bay doesn't have resources for people who find themselves in this position. My old housemate in west Oakland, in her early 30s and well-educated, but with health issues, is being forced from the bay. She grew up in Berkeley and Oakland. This is her home. I'm sad.