[pluma]

It only "works" in the sense that users buy it because it's shiny.

Unless you're saying the only point of the iPhone is that people buy it, that isn't sufficient.

[raphael_l]

It works for Apple and how they want it to work. That's why it is designed well.

Design is very much depending on the intended outcome. Apple wants to sell devices -> design them so that they get bought (make them "shiny", as you put it ;)). Of course this is not the only point of what Apple wants, but it certainly is the biggest one.