Edit: Re your edit, I still think that designing the actual hardware that the user interacts with directly is equally difficult to design as the software at any

Edit: Re your edit, I still think that designing the actual hardware that the user interacts with directly is equally difficult to design as the software at any level. The fact that the iPhone has 4 buttons and a switch is a huge design decision. The size, shape, texture, reflectiveness, responsiveness, and tactile feedback are parts of the design that need to be considered and are not malleable once released.