But now, Apple doesn't have as much leverage. If they walk away from negotiations and say "Sorry, no more AT&T iPhones," they're losing all of the customers that stay on AT&T and buy Android devices. And AT&T loses all of the customers that switch to other networks so they can get new iPhones.
Apple did try to do something about exploitative text message pricing when they introduced iMessage. AT&T's response was to stop offering anything but unlimited texting plans.
You've always been able to buy an unlocked phone with no crapware and no restrictions. The problem with the iPhone is that even the unlocked phones are restricted and locked-down, which is a first.
That said this conversation is about unsubsidised, unlocked phones. Not phones bought through carrier channels. Apple are breaking new ground by selling an "unlocked" phone, for an unsubsidized price, but still pushing carrier restrictions on it.
> Apple won't help me because they agreed to block on-device APN editing for certain carriers, including AT&T, even though this negatively impacts people who are not direct customers of AT&T, and even though there is not one single other unlocked GSM phone model on the market besides iPhone that imposes this restriction on users or hands over this kind of control to carriers.
Unless I'm misunderstanding your argument. Are you suggesting that Apple is beholden to _all_ of the carriers severally now, because of risk of losing their dominant slice of marketshare?
They no longer get the same leverage that they had while offering an exclusivity agreement on the first iPhone. If Apple were to walk away from AT&T, both companies would lose a bunch of money. It's something of a "nuclear option," and Apple doesn't care enough about unlocked phones to waste their limited bargaining ability on it.