Bret Victor's "Brief Rant on the Future of Interaction Design" is an eye-opening look at the poverty of the current options for computer-human interaction. Victor argues that our hands have enormous expressive range and sensitivity, but our devices accept only pokes and swipes from them, and only provide feedback in the form of a little bit of haptic buzzery. He persuasively argues that expanding the repertoire of I/O using hands will produce interfaces that are richer and better:
Notice how you know where you are in the book by the distribution of weight in each hand, and the thickness of the page stacks between your fingers. Turn a page, and notice how you would know if you grabbed two pages together, by how they would slip apart when you rub them against each other.
Go ahead and pick up a glass of water. Take a sip.
Notice how you know how much water is left, by how the weight shifts in response to you tipping it.
Almost every object in the world offers this sort of feedback. It's so taken for granted that we're usually not even aware of it. Take a moment to pick up the objects around you. Use them as you normally would, and sense their tactile response — their texture, pliability, temperature; their distribution of weight; their edges, curves, and ridges; how they respond in your hand as you use them.
There's a reason that our fingertips have some of the densest areas of nerve endings on the body. This is how we experience the world close-up. This is how our tools talk to us. The sense of touch is essential to everything that humans have called "work" for millions of years.