So far they have resisted, and it shows in the still-uniformly wretched condition of most American towns. For if environmentalists were leading the way, they would be doing more advocacy work in our urban centers, marching for new buildings. I know one particular environmental lawyer who did build a new house in town and then strenuously objected to the suggestion that he put trees in the planting strip along the curb in front of his new house. He preferred a landscaping fantasia of pine trees in his front yard, and he even built two mini-berms to accessorize it. But the truth is, the community cannot make a decent residential streetscape unless there is agreement, for instance, that all neighbors will respect the need for trees in the planting strip.
Diversity is meaningless outside orders of unity, particularly where the human habitat is concerned.
Diversity, for its own sake, is exactly what makes the standard American commercial strip such a ridiculous and tragic place. That is not the problem. Nobody comes back from a trip to Italy complaining that the hill towns all looked the same. The urbanism of Baron Haussmann's Paris is so rigorous that the casual observer could easily mistake the Blvd. St. Germaine for the Blvd.