A leaked memo for T-Mobile reps shows what they are supposed to say to customers who don't want to give up the old minimum. The reps are told to point out that with the 2GB of data, customers never pay more than $20 a month while the 200MB plan had an overage charge of 10 cents per MB up to an additional $30 per month. With the new plan, if you exceed the monthly 2GB cap, your data speed is subject to be throttled. If the customer is persistent about the 200MB, the rep is supposed to downsell him into a featurephone. And after seeing, say, the Samsung Galaxy S III at work, it is hard to think about going back to a non smartphone.
Of course, heavy data users have the option of signing up for T-Mobile's Unlimited Nationwide 4G plan which removes the threat of throttling from the picture.