There are efforts to build more. search for Scott Weiner if you are in California, and 'yimby' is another keyword.

My personal opinion is that if you want to get approval to build an office building, part of that approval would be talking someone into building a similar number of housing units nearby. I mean, not that they should be owned by the same entity; most of us don't want our housing directly contingent on our employment, but you need to build offices and housing in sync, otherwise you get crazy traffic problems.