I was taking another look through Morgan Stanley’s Mobile Internet Report from December and a graph caught my eye that pretty much sums up the reason mobile carriers are doing away with the all-you-can-eat pricing model.

It’s somewhat hard to see in the image above, but if you’re interested, click through to the report and jump to page 55.  The graph represents the growth in data traffic for NTT DoCoMo and Vodafone for a four year period from Q2 ’05 to Q2 ’09.  The results show NTT’s data traffic jumping from about 30% to around 90%, and Vodafone jumping from the mid 40s to north of 70%. Many people noted AT&T’s similar jump with the release of the iPhone.

With data traffic consuming that much of the network, it’s not surprising that the network operators would begin to package bandwidth the way they package minutes.  When your data traffic goes from being less than a third to ninety percent in four years, there is a pretty good driver for changing your pricing models.

Data used to be viewed as an add-on service that complemented your traditional voice service.  In that context, all-you-can-eat made sense.  However, data is rapidly becoming the principal technology of wireless carriers.  In that model, it makes sense to a) price differently, and b) use price as a means of traffic control.

A lot of people complained when AT&T made the move to tiered, metered billing.  However, those tiers will likely affect consumer behavior, preventing the heavy users that are the bane of wireline networks.

Just as $4-$5 per gallon gas changes the way we drive, high prices for bandwidth will change the way we consume data.  That may annoy consumers, but it may improve the network experience.