They were the cheapest of the big carriers for sometime, still don't know if they are. That's being competitive to me. All of the major phone companies are just as guilty as AT&T of "nickel and diming".
Huh? What world do you live in?
AT&T offers no unlimited data, their plans are sky high, etc.
T-Mobile offers unlimited everything starting at $35 per line (two line minimum), yes they have throttling, but you can pay a little extra to get more high speed bandwidth. That being said, even when throttle my wife's Android phone has a faster data connection on T-Mobile than mine does when not throttled on AT&T.
Sprint has lower priced plans than AT&T, so does Verizon.
Of course, then you look at the prepaid market like Straight Talk and you can get even cheaper (and have all taxes included).
I still maintain that a nationwide Wi-Max (or some equivalent) network and phones that can connect to it could be a viable and inexpensive alternative though.