In many ways, modern phones are power user devices. People use the interface all day every day — and are more or less stuck with using it. Two results: (1) Users get extremely frustrated over minor points of friction in frequently repeated processes. (2) It’s reasonable to expect huge (semi-involuntary) time investment from users to overcome steep learning curves.
Result: a UI overstuffed with semi-hidden affordances designed for repeated workflow, not for learning or for low cognitive burden.