Printers are “cheap” because ink is expensive.
DVD players were “cheap” because movies were expensive.
If you get a cut of the apps people buy for their phone, you want them to be using your phone.
Etc.
Then there is price competition.
I still have an old Radio Shack catalogue from the early 70’s that lists a bulky and simple hand calculator, “with memory” for $149.
It’s about time Moore’s law applied to smart phones.
You now have a scientific calculator as a simple app on your iPhone. Along with the compass app, the maps, and the music, that along justifies the price. And I'm just scratching the surface of what a modern iPhone can do.
BTW, it also makes phone calls. If you want to stay old school.