OTOH, millions of people paid much more for mobile phones because of it's touch screen user interface.
Are you sure? Touch screens dramatically reduce
the appeal for me. I hate the paralax, the fingerprints, the scratches, and the sometimes-fickle operation.[/quote]
True. I have a clamshell mobile ("flip phone") because it sllows to acceppt a call by flipping it open - instead of attempting to hit a tiny button which can be located only visually, not haptically. I seriously dislike the idea that I'd have to constantly watch my fingers to make sure that they hit the right spot.
I know that there are applications where touchscreens make perfect sense. A good example is the GrandMA, a lighting console. It has three touchscreens, which are typically used as "soft buttons" to recall lighting scenes. During a major event, there maybe hundreds of stored presets, accessible via dozend of touchscreen pages. I typically hit the touchscreen buttons with my knuckels to minimze fingerprints.
Still, the GrandMA has a large number of conventional buttons and sliders as well. At a typical sustained rate of (roughly) two keypresses per second, only the conventional buttons make sense. Especially if the operator has to keep his/her eyes on the stage - or on the touchscreens, where he/she prepares the next scenes while simultaneously running the show with the other hand.
Okay, this is the special case where the flexibility of a touchscreen can be combined with the efficiency of high-quality buttons.
But I digress. Why do mobile phones need touchscreens? To add more flexibility? So, instead of being perfect for a job as a telephone, they can be inefficiently used for a wider range of jobs?
Nope. The touchscreen has no funcitonal purpose. It's only there to look cool in TV ads. And TV ads are the reason why people buy stuff.
Except the three enlighted people, who coincidentally happen to participate in this thread
PS: to further digress, I need to mention that many modern lighting consoles use the same type of mechnical buttons asthe models which were in in use 30 years ago.