I think you're assuming a lot about the relationship's power dynamics and what contracts are at play that may have been written quite a while ago. Also forgetting that more often than not it's the telco that's blocking or bottlenecking updates. The reason Apple was able to do what it did is because they provided the software and hardware and were able to leverage the demand for it against the likes of Verizon (probably the most notorious blocker of updates no matter how critical they might be).