Well I'd argue that suburban areas in Europe are sometimes even less dense, yet still there's much more places to go to. Maybe "bad" is a "bad" word here, but I think this is just a matter of urban planning. If you build a four-lane highway instead of one-lane street it discourages people from walking. Have there been a better public transport like buses, trams or subway, people wouldn't drive so much either. If they have to drive anyway, because there's no another option, they can drive further and thus don't care if the place they are going to is 5 miles away or 10. I guess the cities would have to make the first step and plan the new neighborhoods as more dense, more urban environments. Housing developers usually only care about earning money, so if it's cheaper to build everything the same way as before they'll do it no matter what. And people cannot even oppose it, because rents/house prices are already stellar in the Bay Area compared to other places even in the US. This makes it a vicious circle.