Old cities that were built with foot traffic in mind as the principle mode of transport do very well when cars are banned from some streets. I'm thinking of Boston and the Downtown Crossing area, where the street is closed to traffic, which has drawn shops and restaurants, and the waterfront has been redeveloped with pedestrians in mind.
Even cities laid out for cars can profit greatly from banning traffic from an area, I'm thinking of Third Street Promenade in Santa Monica.

I'm not sure banning all traffic makes sense, but setting aside pedestrian areas creates a wonderful cityspace.

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“ The subjects of every state ought to contribute towards the support of the government, as nearly as possible, in proportion to their respective abilities; that is, in proportion to the revenue which they respectively enjoy under the protection of the state.”

Adam Smith , The Wealth of Nations 1776

"We have always known that heedless self-interest was bad morals; we know now that it is bad economics"
FDR's second Inaugural Address