It's not all that often you can accuse someone of being MORE short sighted than a C level executive. Is "the spectrum" full? Oh hell no. Do you really want to see that day? I assure you, no. But more to the point, ATT is aware, as anyone with a brain and a few minutes would be, that in large cities the spectrum may not be full, but the land to build a cell site... that is. At the very lowest level, the problem with adding bandwidth to crowded cities is a matter of real estate. In several senses, actually. First, you have to find some. Then you have to plan around the neighbors. Oh, that 43 story building next door is made mostly out of glass, steel and carbon. It sucks up and refracts your signals all to hell and back.
In short, it's not quite so simple as you pretend it is. On the other hand, screw ATT and verizon too. Bunch of money grubbing assholes, and they have been for about 60 years now. I say that as a long time ATT customer. Unfortunately there are no better options. Sprint's coverage is a joke, Verizon has dollar signs where their brains should be, and T-mo is desperately trying to sell itself off, which doesn't make signing a contract all that appealing. I pray that google takes Motoral's handset department, and combines it with a big fat fuck you to the telcos and starts offering GoogleMobile (combined Wifi, Wimax(whatever), cellular).
If google gave you some free services, or a bit of money to turn your wifi router into a public backhaul, would you? Presuming of course you had some level of QOS control.