1.5 years ago, "Hey Steve, the conceptual developement team are working on the next phone after the 4s. We think this time we might want to make the screen bigger, and we hope that the processor will be faster by that time too. What do you think?." Steve:"Well, I don't really agree with the bigger screen but what the heck, people will buy us now no matter what, go ahead".
People actually think that the higher ups actually invent the stuff when big products come up. When a company is small (like apple was in the 80s), I would agree. When you have large companies, there are teams of people dedicated to just parts of a particular product. The real ones that are creating these great products are the designers and project managers that are putting it all together.