Basically, what everyone wants is for companies like T-Mobile to be a dumb pipe. They invested in spectrum and a network, and they should just lease that network for cost + profit margin. Instead, they want to milk it. They want you to pay more for particular packets. They want the rest of the Internet to pay more for particular packets. They want to inject their own ads into unaffiliated websites. They want to build a marketing profile based on what sites you visit, and send you "offers" based on this. Right now, that is all technically possible, so they'd be defrauding their shareholders if they didn't try. But, we can of course say "no" and route around the damage. Apple is letting their customers say "no", and that means T-Mobile is doomed to irrelevance, and that's a great thing. Infrastructure should be infrastructure.
(Can you imagine what it would be like if other utilities did this kind of shit? Your water would cost less if you were using it to run a Coke-branded soft drink dispenser, but not a Pepsi one. Or, Dell computers could get electricity at a 10% discount, but not Asus ones. It would be unthinkable! But with these big ISPs, it's mandatory.)