Which is the advantage (to users) of the self-appointed benevolent dictator for life model.
What do users want? Something that's cheap, easy to use and unlimited.
What do the carriers want? Something that's branded to them and customised so they can upsell features. (Which requires an ecosystem they can customise, such as BtG.)
What do the platform vendors want? Ecosystem control so they can be the gatekeeper selling apps and ads.
I hate to say this as a long-term Mozilla fan with a strong distaste for iOS, but the most user-friendly model appears to be tied to platform vendors, not carriers. They are the ones with an incentive to maximise service; carriers, OTOH, have demonstrated a very noticeable tendency to salami-slice everything. Want your apps? Sorry, got to go through your network's app store. (And devs, you now have to negotiate with hundreds of vendors, each with different rules.) Want to use more than Facebook and YouTube? Sorry, that's the 'enhanced web' package. (Some have already done this.) Want tethering? Sure, that'll be £30 per month. And, once the carriers have the ability to have their own branded and locked-down smartphoens, just wait to pay a surplus to use an 'unsupported device' like an iPhone.
The carrier-controlled model has been tried before, and found wanting. Returning control to them could set the market back five years in one fell swoop.
If the power is somewhere, I'd like it to be with Apple or Google, not AT&T. At least they tend to aim for making their customers happy, when AT&T seems quite intent on screwing me over.
Conversely, taking power away from someone is usually why you keep the system closed.