OK, you are probably saying, surely it's gesture-based interfaces that are important now rather than touch screens, and they allow you to stand back. This is a fair point, and the Minority Report kind of remote swipe gesture approach, which now shows up in several TV drama strands such as CSI Miami and NCIS Las Vegas, certainly looks fun; but it lacks the precision of a touch screen and is more like throwing things around the room. There are situations where a big touch interface would seem ideal, such as 'you are here' location maps in museums and even cities.
If you've never seen this kind of thing, here's an example from 2008 ... although MIT was prototyping this kind of thing in the Put that There project in 1979. This is G-Speak from Oblong Industries.
Touch screens go back to the light pen interfaces of early computing. They could be easy to implement (you could even get one for the 8-bit BBC Micro in the 1980s) and easy to program. Detecting a finger touching a screen is more difficult. Early examples used infrared beams shooting across the screen from the surrounding bezel. What we now see relies on electronics detecting the presence of a finger on the display ... the so-called touch current ... using a conductive but transparent layer.
There's an interesting story on Wired UK at the moment, GeekDad's daughter reimagines interactive TV, where the writer's 16 month-old daughter really likes the touch interface on her (yes her) iPad. She's a fan of CBeebies In the Night Garden and one evening tried to drag a character from the iPad screen onto her bed ... and was frustrated when it didn't work.
Here's another telling quote
Our TV screen, fridge door and bathroom mirror are all testament to this, upon which her toddler-sized sticky-fingered smears (or should they be gestures?) give a real insight into the way in which these devices and appliances could instead be more intuitively manipulated.In the metaphorical vehicle in which the family is driving towards the future of interactive technolgy, the kids are sitting in the back shouting 'Are we there yet?'.