If 2 GB is excessive, why is AT&T selling 3-GB mobile data plans?

When AT&T first implemented its throttling policies on unlimited mobile data plans last fall, it justified the move by claiming it had to limit the “extraordinary” consumption of a few greedy smartphone customers. We’re starting now to get a glimpse of what AT&T means by extraordinary. It’s only 2 GB – a full gigabyte less than it sells its newest customers under its most-common data plan. But AT&T just overhauled its plan pricing. It’s newest mid-tier plan charges customers $30 for 3 GB. Why is AT&T inviting new customers to consume a full gigabyte more of data while telling older customers – who pay the exact same monthly fee – that 2 GB of data is excessive? My bet is that the former is really a false invitation.