[nwiswell]

Because the modern world depends on the automobile, and from a utilitarian point of view the modern world has still had a positive effect on life expectancy.

Car culture should not be a foregone conclusion, though -- you are right about that. Many European nations -- the Netherlands being the typical example -- have done a pretty good job of fostering a bike culture in their cities. But us Americans sure love our cars, and so it's ultimately a political question, not a moral one.