An excerpt from Jony Ive: The Genius Behind Apple’s Greatest Products by Leander Kahney:
Jony in particular had always had a deep appreciation for the tactile nature of computing; he had put handles on several of his early machines specifically to encourage touching. But here was an opportunity to make the ultimate tactile device. No more keyboard, mouse, pen, or even a click wheel—the user would touch the actual interface with his or her fingers. What could be more intimate?