That's a very odd statement. This sort of thing is very efficient in terms of land use, energy use, and transportation costs. If anything, one might consider it

That's a very odd statement. This sort of thing is very efficient in terms of land use, energy use, and transportation costs. If anything, one might consider it too efficient in terms of required control -- having a sanitation worker strike would be absolutely disastrous for a million people at once. It needs much more attention paid to means of governance and politics than a regular city of a million people, because everyone is living in the same building. It's not very good at growing food or producing energy, but those are not things that we expect cities to do today.