You may have seen this video that Microsoft put out last year of its vision or technology in the near future. Virtually all of the fancy tech depicted centers around touch screens, with a healthy dose of Minority Report. Somewhere out there, possibly in an underground volcanic bunker, I swear there is a cabal that is overseeing touch screens' ongoing takeover of virtually all of our electronics. In ten or fifteen years, cars will have no controls save a 21" glass panel where the steering column used to be. Thanks largely to the trends kicked off by the iPhone and iPad, touch screens are practically ubiquitous today; most people use them on a daily (or hourly, or minutely) basis and tech companies are always thinking of where to put them next.
Besides the fact that everyone is trying to imitate Apple, I see two explanations for touch screens' popularity. From the users' perspective, touch screens offer a directness surpassing that of traditional mouse-and-keyboard interfaces. Instead of pressing buttons or moving a pointer that controls what's happening on screen, you directly manipulate what's on screen. This is supposedly more intuitive, and touch screen-equipped devices are making tech nerds out of people who would have had little interest in computers twenty years ago. From a developer's perspective, touch screens allow the user interface to be decided by the software, rather than locked in by the hardware; the abundance of touch screen-based app toolkits out there makes it relatively easy to harness their popularity for your app.
So popular are touch screens that people generally seem to take it for granted that they are the future of mobile computing, if not computing in general. All the hottest new phones use touch screens, with cheaper, keyboarded "feature phones" seemingly held onto as a concession to the old-fashioned. Virtually all high-end MP3 players (the gadget that prompted this post) use them as well. I'm not saying that touch screens don't have their aforementioned merits, but generally consumer culture seems virtually blind to the disadvantages of touch screens; they are categorically seen as a shining icon of progress, putting them on more things is a "good thing", and so on. Here are the problems I see with them.
Lack of tactile feedback. This is by far my biggest problem with touch screens. You may be able to display a pretty, near-life-sized keyboard on an iPad, but an interactive display on a glass screen is a pale shadow of even a cheap physical keyboard, much less a nice one like a Model M. The big difference is that a glass surface has no feedback as far as your sense of touch is concerned; unlike the complex surface of a keyboard, a touch screen is completely tactically uniform and there is no way to orient yourself on it by touch; you have to work by sight alone. (Which isn't made easier by the fact that your hands are occluding part of the display)
So basically, the whole touch screen "movement" really underestimates the power of our sense of touch. It's a whole dimension of our senses that can greatly increase the speed and ease of use of a device, and touch screens completely do away with it. For an example, I used to own an 80GB iPod Classic before it was lost/stolen. While walking around the U, I got pretty good at playing/pausing/skipping songs without taking the iPod off my belt or looking at the screen at all. Eventually I even got the hang of binary-searching through my music without looking by picking a song, checking what it was, and then accordingly scrolling closer to where I knew the song I wanted was. It was a cool cooperation between my senses of touch and hearing made possible by the good old "click wheel". On my iPod Touch, reliably pausing the music without looking is difficult enough, and seeking through my playlists is virtually impossible. Or, of course, there's the fact that without my iPod Touch's extensive auto-correct feature, I would type more slowly than I do on my 12-button phone thanks to muscle memory.
So that leads into my next point: because of how they (ironically) take our sense of touch out of the picture, touch screens tend to be less efficient than conventional interfaces at the same tasks. They may be more intuitive in many cases, but for keyboard-shortcut-hungry power users like myself the difference can be frustrating. It doesn't matter when you're playing Angry Birds, but it makes it hard for me to take iPads seriously as business devices. I wonder if I'll see any around Seagate next week and beyond?
On a related note is the lack of precision of touch screen interfaces. Unless you use a stylus, which are so early 2000s, or cut your fingernails into points (which apparently works), your fingers are quite a bit bigger than a cursor, which makes work requiring pointer precision (like selecting a specific point in some text, or image editing) difficult.
Another thing is the limited number of actions you can do on a touch screen. Let's see...you can tap, slide, pinch, rotate, swipe...I can't think of any more; certainly those are the most common ones. And like the standard keyboard shortcuts, they have been pretty well standardized; a tap is a click, sliding pans you around, pinching zooms in or out, and so on. Some of these may or may not make sense of applications, and in general there are simply fewer things you can do on a touch screen relative to many mechanical interfaces with diverse buttons that can be combined. Sure, zooming in and out may be a breeze, but copying, pasting, undoing, etc. are no longer single-gesture muscle-memory actions like they are on a keyboard. And allowing more complicated actions via multitouch that correspond to more things is generally unintuitive and against the whole point of the touch screen. (I still have no idea what three and four-finger swiping on a MacBook do and why)
A note: in my graphics class we did see some pretty cool demos of two-handed touch surfaces for rapidly navigating and designing 3D models in virtual reality. Certainly for some tasks, like 3D drafting and viewing, touch screens are a great fit. But these demos were highly experimental and certainly exceptional, and I was speaking to more diverse and common tasks.
Touch screens are certainly a cool and valuable technology, but recognizing these limitations, I for one hope that they keep mechanical controls for our gadgets around for the foreseeable future.