The internet boom has made it easier for people to interact, blackberries, corporate wi-fi services have also ensured that no one anywhere is 'left out'. Rolla for instance which is referred to as the middle of nowhere has one of the best connected campuses in the entire midwest region.
Now considering that all this connectivity exists today then why do still people crave to live in the urban jungle. If you just consider the monetary aspect over here it would definitely be advantageous to stay in a place like Rolla. As far as commodities go the essential ones will always be available at the local Walmart and if you want something specific then you could always pick it up online.
The bottomline thus comes to the fact that we prefer being around people. To be more specific we prefer being around 'like minded people'. Yes most of us often dream about owning our own private island but when it comes to actually moving permanently then I doubt how many of us would actually go for it.
In the US there is something about megacities like NYC, SFO, Chicago, LA. In todays world being around the right people more often than not is the reason for people relocating to these megacities. The $ factor is there obviously but you are exposed to a whole lot more when you are based in the cities. You learn to live by your watch, subway times become more important than anything else and most of your routine is based on the subway schedule.
And once you are into this system it becomes really difficult to let go and move to a laid back country lifestyle. Maybe several decades down the line we consider health issues and then relent to moving to something less stressful and slow.