"I often think of what OS X would be like if Apple assumed only Pro users would use it and everyone else would be on iOS."

It's an interesting thought but quite feasible. Open up any Apple "Pro" app like Logic Studio, Aperture or (more recently) Final Cut Pro X. The look and feel is quite different than the rest of OS X. Things are smaller and far less intuitive (they are hidden away). Apple knows that amateurs will stick with Garageband, iPhoto and iMovie, all of which feature large, intuitive interfaces. I like that they are not afraid to make their "Pro" apps heavy-duty.