This reminds me of how Khan only thought in two dimensions while chasing the Enterprise in that nebula, while Kirk was navigating in three.
Yes, data is data... but the amount used per instant time period is the limiting factor, not the total over a long period.
Consider an un-upgraded cell site with 10Mbps backhaul. If 100 users are connected and they're all surfing the web or doing email, with each randomly using an average of 1Mb every ten seconds, the backhaul can handle it. If there's a slight glitch, the user doesn't notice it.
Now consider if 10 of those users are doing video streaming at 1Mbps. Oops. They require the entire backhaul capability, leaving the other 90 people with nothing.
It's as if you were allowed 1,000 gals of water a month. Using that allocation slowly over the entire month... such as taking a bath every day... doesn't harm anyone else's random access to the shared water main. Opening several fire hydraunts will.
So what? I can use Skype over 3G. AT&T has no right to charge me to use a certain type of video traffic when I am already paying data. The concept is absurd. Charging me extra for using a certain protocol? All they're doing is making a feature useless and pushing me to another service.