Don't forget the element of time (something which New Urbanism is critisized for, as in 'you can't build a real town all at once!')
Time can bring greater density, more mix of incomes and use, greater connections to transportation, and certainly the patina of 'real' places. Look at photos of Boston's Back Bay or Nantucket, or New York City's Upper West side in the early days.
The reason even New Urbanist greenfield projects are more than just suburbs is that it is possible to walk once you are there (and interesting enough to walk from your house to any transit), and there is usually the opportunity for retail, office, civic and mixed housing, even if it is sparse in the beginning. It can evolve and change - in a good way.
The problem with the suburbs is they are inert - they will stay the way they are forever. And even if you arrived to them by light rail, there is no 'there' there once you arrive.