[Sam Hill]

The problem for many metropolises - and even for many cities in the core of those metropolises - is that they were largely planned and built around freeways and the automobile. They're stuck with those freeways now because it's the heart and soul of their transportation systems and they don't have the density to support alternative transit options. Removing their freeways would cause parts of town that were once minutes away to become hours away and it would be economically stifling.

So I guess it depends on the city. Some could possibly do without; some could do with less; and I know it's blasphemous but some would actually be better off with more.

Politics also plays a role. It's more feasible to change zoning, increase density, and add or remove transportation options in some cities than others. There are vast, automobile-dependent parts of my town that will never change. If their local government(s) even tried, it would be "off with their heads!"