It's impossible to believe this was incompetence, not malice. No well-intentioned person could have looked at Detroit and said, I want my whole nation to look like that.

It reminds me of the Enclosures at the start of the industrial revolution. That also massively changed the nation. The part of the ruling class, who were just incompetent and not malicious, may have thought that genetically changing the population will also work out for them. It destroys everything instead.