This paradigm shift didn't happen post 9/11. It happened on 9/11! This method of attack was essentially shut off during the actual hijackings themselves. Flight 93 was the famous story. The people on the Pentagon airplane knew what was happening but couldn't react fast enough. IMO, the reason the terrorists lost the element of surprise was that they underestimated the robustness of our ability to communicate. They understood the value of information warfare when they shut off transponders, but they didn't possess even an infitesimal fraction of the ability they needed in order to conduct an adequate infowar attack to maintain the element of surprise. Like it or not, bin Laden is a smart guy and he understood this; hence, his decision to scale down the attack.

If the bad guys had conducted an effective infowar effort cutting off (as a minumum) all types of voice and data communication, we may not have concluded that the attack succeeded because of the procedure to cooperate with hijackers. Then, where we would we be?