On the other hand, they need growth (market expects that) and it is harder and harder to attract completely new iPhone customers. Increasing the amount of money extracted from those who are anyways buying iPhone is one option.
More expensive models can also boost the sale of cheaper ones among certain customers. This can give the brand a luxury image. Of course if done wrong, it might also drive some other customers away.
> On the other hand, they need growth (market expects that) and it is harder and harder to attract completely new iPhone customers.
Just introduce an "Hackability Edition" of the iPhone which has many of the features that make nerds drool, as ability to allocate executable memory in apps (thus making JIT possible), ability to sideload apps, replaceable battery etc. and Apple will have completely new iPhone customers.
More expensive models can also boost the sale of cheaper ones among certain customers. This can give the brand a luxury image. Of course if done wrong, it might also drive some other customers away.