I think that the data cap moves we are seeing in the data communications sector represent a market-wide trend to protect the existing profitable "value added" services such as voice calling and premium television services. Companies seem to be afraid of becoming just another "dumb pipe" as connection speeds get fast enough to handle third party "value added" services (e.g. Netflix and Google Voice). These companies believe that, by using data caps and unregulated third party data usage meters, they can ensure the protection of their highly profitable "value added" service sector. In many respects, this practice represents a trend of "predatory pricing" and "refusal to deal" in the communications industry.
For example... In the cellular world, the 5 GB data cap effectively tolls previously "free" services such as Google Voice. On the broadband side of things, a 150 to 250 GB cap effectively limits the ability of Netflix and Hulu to compete with the first party in providing premium high definition video content.
In many ways, these data cap moves are representative of an anti-competitive protectionist oligopoly. They also represent an end-run around the principals of network neutrality. By using unregulated meters that only bill for third party network usage, these companies have effectively "rigged the pump" to ensure that they can charge almost any rate for almost any service. Better regulation and oversight is needed at the Federal Government level to ensure fairness and competition in this otherwise anti-competitive industry.