AT&T has enough blame, but what about Apple? It takes years to expand a Wireless Network. Given that.......
1. What forecast did Apple give AT&T as far as projected US sales of iPhones and estimated average bandwidth per user? I bet it was far lower than anyone had ever expected. Without accurate projections, how could any wireless carrier build out a capable network ahead of the demand? Remember, too, that when the iPhone first came out, the APP Store was not even on anyone's radar. Apple kept adding features without first checking for network capacity.
2. Why did Apple choose just one US Wireless Carrier? Remember, this was Apple's decision, not AT&T's. We all know the reason why....higher subsidies from a single carrier (versus multiple carriers). So all that money that could have been used by AT&T to expand the network is sitting in Apple's bank accounts.
While your points are very valid, AT&T has made some serious bank with the iPhone. Millions of new subscribers, rates and fees for new customers and clients that never had a need for a data plan, etc. have all added up to money in their pockets. While certainly the immediate increase in network demand has been enormous for AT&T, they have had plenty of time to add more towers and improve on their overall service. This recent news suggests AT&T has been researching the population density of iPhone users and adjusting their service accordingly, but why did they wait over two years to adjust? Perhaps the downturn in the economy is resulting in more fiscal conservatism and growth from corporations, perhaps AT&T wants to invest in their upcoming 4G network, who knows. It seems apparent that with AT&T's decision on holding off MMS for the iPhone that they are concerned with network drain, otherwise any intelligent corporation would not hold off on a profitable service (depending on how AT&T decides to charge customers for MMS). In all, it seems obvious that the 5 year road map for the iPhone wasn't thought out 100%. Apple surely kept many aspects of their product "secret" (as they tend to do) from AT&T and AT&T most definitely kept a few cards up their sleeves, in the end, the customers lost (somewhat) while two companies raked in cash.