It would be great if (new)cities where designed in small nucleus of 2 or 3 miles in diameter with homes around the business and commercial center, all surrounded by more or less green zones. This nucleus could be connected by subway or train. Obviously that is not going to work with old cities but here in Spain, Madrid has seen a huge grow this last decade (every thing is halted now but still you can see the town planing from the air) and the town planing has been non existent to disastrous (huge concrete islands surrounded by highways). Now you have all the inconvenience of vertical cities combined with the inconvenience of the suburbs...(No green zones, cant go walking anywhere...).

Obviously political and economical interest of the terrains to be built have priority over all this nonsense...