That blog post is so short-sighted and sad it's unbelievable.
Cities within cities are not new concepts. Many have been proposed before...look at the giant Chinese pyramids. All are great in theory, but are also very expensive to build. One has to weight up the pro's and con's of such developments. For example, a few have been proposed as populations rise but land sizes stay the same. They're extremely high density and as a result are great for space-constrained cities.
I personally don't like the idea of them, as they propose a whole new concept of city that will be hard to adapt to. They've also got to take many things into account such as safety. Can you imagine a run-away fire breaking out in one of these things? The Chinese proposal could house 1 million people. Architecturally, the pyramid in question looks like something out of a sci-fi movie than a logical 21'st Century building. People complain about skyscrapers detracting historically from cities...can you imagine how they'll complain about this?
However, the day may come when we have to look into these things for one reason or another.
