T-Mobile has moved at speed to offering just one type of unlimited data plan. Customer response has been overwhelmingly positive — shocker! — but T-Mobile’s One plan leaves people who don’t want to pay the price for unlimited data out in the cold.

So, shortly after revealing the T-Mobile One plan, the network also announced KickBack, a program that takes $10 off for every line that uses 2GB or less per month. It sounds insignificant, but since adding an extra line onto a family plan is $20 per month (after the fourth line), it means that you can add low-usage extra lines onto your account for just $10 a month. That’s perfect for adding young kids or grandparents who don’t use all that much data, or for spare or secondary devices.

But unfortunately, T-Mobile isn’t going to keep KickBack around. TmoNews reported earlier this week that T-Mobile was closing KickBack enrollment after April 12th. Existing customers should still receive the discount, according to T-Mobile’s support page, and existing customers with an eligible line will still be able to activate the benefit, but you’ll have to call customer service rather than doing it through an app.

On its own, this isn’t a huge deal. Carriers change pricing all the time, and they don’t normally send out a press release to announce it. But T-Mobile famously brands itself as the “Un-Carrier,” and part of the concept is that it doesn’t pull “carrier” moves, like quietly changing up the pricing. It would be a very different story if T-Mobile publicly announced the change a month in advance, giving customers time to switch, but it didn’t: We only learned of the move when the company changed the KickBack support page and someone at TmoNews noticed.

In a statement, a T-Mobile spokesperson said ““KickBack was designed for customers who didn’t want to use a lot of data – but our customers love data. T-Mobile customers use more data than anyone else in the industry and as a result, we’ve seen very low customer activation. We have decided to instead focus on features that more customers want.”

If it’s true that KickBack had such a low enrollment rate, why kill the plan at all? Ostensibly it isn’t costing T-Mobile much money and it’s certainly a hit among people who use it, so why kill a popular feature?

Make no mistake: T-Mobile is still the most straightforward of all the big carriers, but that’s really not saying much. Being the best of a bad bunch isn’t hard, and T-Mobile has pulled stunts like this before. Just because the Un-Carrier is cheap, doesn’t mean the company is on your side. Cool dad persona or not, CEO John Legere still has shareholders and corporate interests, and those quarterly profits don’t make themselves.

Chris Mills has loved tinkering with technology ever since he worked out how to defeat the parental controls on his parents' internet. He's blogged his way through Apple events and SpaceX launches ever since, and still keeps a bizarre fondness for the Palm Pre.