There are cities that get by on their good looks, offer climate and scenery, views of mountains or oceans, rockbound or with palm trees; and there are cities like Detroit that have to work for a living, whose reason for being might be geographical but whose growth is based on industry, jobs. Detroit has its natural attractions: lakes all over the place, an abundance of trees and four distinct seasons for those who like variety in their weather, everything but hurricanes and earth-quakes. But it’s never been the kind of city people visit and fall in love with because of its charm or think, gee, wouldn’t this be a nice place to live.