There's an argument that forcing the city to "spread out" rather than "up" has been partly responsible for the rapid improvement in crime and livability in many parts of the city over the last decade. What would H St NE or Upper 16th St look like if one could just build huge buildings in Dupont and Adams Morgan.
I don't think that dog will hunt. Some of the safest places in Chicago are also the densest (say River North with its towering residential skyscrapers). Same for New York (Manhattan is way denser than the Bronx).
The reason DC has gotten nicer lately isn't the sprawl. It's because it's become a major target for young professionals, which have driven the poor people out of many parts of the city.
Living in a city has become desirable again. People who can't afford to live in the city are being pushed out into the suburbs like Prince George's county. Is that immoral? I don't know.
