The example you gave (iPhone) is itself the result of decades of advances in microprocessors, cellular communication, display tech, and input devices. Apple wa

The example you gave (iPhone) is itself the result of decades of advances in microprocessors, cellular communication, display tech, and input devices. Apple was successful because they put in the resources to develop a device with mass consumer appeal once the underlying tech and engineering allowed for it. You could've asked someone 20 years earlier "why would you want to walk around with a suitcase attached to a phone so you could make calls from your car?" Or you could ask someone 10 years earlier why they would want to carry a small brick in their pocket so they could scribble notes with a tiny stylus. Or 5 years earlier why they would want a phone that ran "apps" when you had to buy them at the store on SD cards and interact via a small resistive touch screen. Few-to-none of these things spring fully formed from the minds of a lone genius. They're the result of identifying new and potentially useful things that can be done with tools that are just becoming good enough to be adequate.