Another important consideration is whether the housing that's built corresponds to the housing that's most desired. A big part of the problem is that, despite strong demand for more walkable, urban housing, that's not the type of housing being built: I estimate a shortage of at least 8 million walkable housing units in the U.S., a deficit that will take decades to cure at current multifamily construction rates.
This again comes back to affordability, as well as regulation: It's much easier and much cheaper to build low-density housing in areas where demand isn't quite as high, land costs are considerably lower, and regulations that limit development tend to be much more lax. Most people will settle for suburban housing when they can't afford the urban housing they prefer, so these non-ideal units still get snapped up. But that's not an expression of preference for suburban housing, that's an expression of preference for not being homeless.
I don't mean for this to be an excuse for the flawed system of development that typifies most coastal cities. Matthew Yglesias writes that housing affordability is Blue America's greatest failing, and I agree. This is simply an acknowledgement that people need a place to live, and when it's illegal or fiscally impractical to build homes for them in one place, developers will build those homes somewhere else — to the detriment of our overall quality of life, health, safety, and environment.
Poole, an unabashedly pro-oil, pro-car advocate, concludes his post lamenting the "wishful thinking" of urban planners who build extensive transit infrastructure even as people continue to choose suburban, car-dependent lifestyles. He's correct that urban planners and other city leaders have fallen prey to wishful thinking, but not in the way he implies. Their failing is in thinking that transit investments alone would create the multimodal, sustainable communities we seek — particularly when those investments continue to defer to cars at the expense of transit users.
Many cities, Los Angeles and Seattle included, have committed to massive expenditures on new bus and rail infrastructure, but few have been nearly so bold in regard to housing development. This has worked out nicely for the relatively few residents that are able to secure income-restricted housing near transit, those that can afford units in the small number of new transit-oriented developments, and especially for those that owned property near stations before they were built. For most everyone else the impact has been sadly limited, and it should be no surprise that as Millennials begin to form their own households, they're choosing to live where new homes are actually being built.