So Sunnyvale has been building a number of apartment buildings and condos around. There has been tremendous back pressure for existing residents (not me but I'm a rarity it seems). The root of their concern is that they don't want the neighborhood experience to change from what they know (or knew) to something they don't know. I talked to some folks who had moved into the apartments near downtown Murphy street. They loved them, easy access to Caltrain, lots of things to do and places to go, they are excited about future growth.
The issue in Sunnyvale at least is that people don't seem to internalize that things change. They won't acknowledge that their cute little bungalow house used to be an orchard (where only birds and perhaps squirrels lived, had we given them a say at City Council there would be no houses anywhere!). They will argue strongly for their values and their memories and opinions of what is "right" and what is "wrong." Meanwhile we have people in their 20's and 30's who don't want to own a car, they want tight walkable spaces with an easy way to get to San Francisco or the airport. Now maybe 20 years from now those same people will be resisting even denser housing or something I don't know.
We could easily build 200,000 market rate dwellings on existing, unused, parcels in Sunnyvale and house close to half a million people in them. But for folks remember empty streets and quiet drives, those people are going to be really really unhappy.