AT&T still maintains the position that less than 5% of its users exceed the 3GB threshold each month.
5% of users hitting 3GB this year means 25% of users will probably be hitting that data limit next year. The amount of data the average person is using is increasing at an incredible speed. To place a limit so low when use is increasing so rapidly makes no sense to me. Plus 5% of about 100 million users means there are 5 million people out there using that much data.
This isn't just an issue of slashdot-types hogging up the network. You're talking about average people at this point.