Housing + Transportation Affordability

Center for Neighborhood Technology: Housing + Transportation Affordability Index

An interesting idea, though I don't really buy the results, since housing as a percentage of income is a choice and there should not be a standard against which we judge this. If I choose to consume more house and less entertainment, who is to say that is "unaffordable". If housing + transport in the exurbs take a higher share of income than the cities, isn't that what the exurbanites prefer, and don't they get better houses than we city folk (i.e. likely to be new with all the amenities and more sq.ft. per person)?