This is exactly the reason why I want to switch from an iPhone to a Droid. The AT&T network, it's terrible. (and other reasons as well, but the main reason is the horrible AT&T network)
Well if AT&T changes their TOS, you can get out of the contract without a fee. I switched to a Droid and am canceling my AT&T account. I can sell my iPhone to cover the cost of the Droid and the ETF.
If they continue to ask, and maybe force people to lessen their data use, I would think that they would have to change their TOS to accommodate those who aren't satisfied because ATT can't pull it together.