The limits of urban design have next to nothing to do with actual ability. It's the fact that you have to deal with actual people, who very often will loudly disapprove of anything that might even slightly inconvenience them no matter how much net benefit it brings.
Everyone with half a brain knows that, for instance, you probably shouldn't need a permit from the city of San Francisco to verify that your new windows won't excessively disrupt "neighborhood character", or that a defunct laundromat should not be a protected historical landmark (which was of course only designated as such after a proposed housing development on the land), or that a truck depot in Harlem is not a better use of the land than a housing complex that would be 50% subsidized.
All of those are real examples, by the way. This isn't a technological or skill problem. It's a people problem, and the robots aren't going to save us there.