[mandibles]

Blame inflation.

If money maintained stable value over the long term, companies could honestly make promises about "lifetime" pricing. These promises were probably made during the "low 2%" inflation of the past, but basic economic understanding would point out that such a plan is doomed.

Better yet, in a deflationary monetary regime, a constant price would net the companies more profit over time. Users would probably clamor for lowered prices on these plans, and companies could advertise "Lifetime pricing plans are now cheaper! You get more for less!"

[terminalbraid]

Inflation isn't a new concept and certainly one that T-Mobile could have (and should have) considered if this were the reason.

[mrgoldenbrown]

No need to blame inflation. Inflation is not new or secret. T-Mobile knew about inflation when it made promises. It could have included an inflation adjustment in their "uncontract". The blame is squarely on T-Mobile here.