The important lesson is not that city planning is unimportant but, rather, that urban development should not be implemented by the public sector alone and that in a democracy, a vision of the future city will best emerge from the marketplace. (That it may turn out to be a messy vision, lacking a grand aesthetic, Jane Jacobs long ago acknowledged.)

Let people vote with their feet and their dollars unless there's a very good reason not to, and err on the side of doing as little as necessary.