And that is where the vibrate comes in.<p>the keyboard is of a known layout, and by marking by feel when you move from one key to the next you know where you are.<p>This allows the keyboard to be operated without looking, much like how most people use a ordinary keyboard today once they are past the hunt-and-peck stage.<p>A big reason for touch screens being a problem in many situations is that you have to actually look at it to operate it. Physical buttons, switches and knobs can be operated by touch alone.<p>Frankly way too much of modern computing relies on sight and sight alone.<p>Also, allowing someone to rest on the keyboard is why long typing sessions are not such a strain on the hands. Without it, the writs has to carry the weight of the fingers continually.