I've got a 28" desktop monitor at home and will soon be going into the ~30" category (after a few more price drops.) It's easy to see how it takes approximately 1" of movement with my wrist (resting comfortably in a natural position) to move the mouse so that the cursor moves from the bottom left corner of the screen to the top right corner, traversing the full 28" distance. It's something so effortless it can almost be done unconsciously.
If I was crazy enough to want a 28" touchscreen sans mouse instead, I'd actually have to lift my entire arm to "press" with my finger of choice near the bottom left corner, then retract my hand and move my entire arm
the full 28" distance so that the finger of my choice can "press" in the top right corner of my screen. If you think that's making a lot of noise about nothing, just try that little experiment for awhile and you'll be surprised how quickly your "pointing" arm will tire. Imagine having to do that dozens/hundreds of times a day. (Imagine how much time you'd spend just cleaning your monitor & hands even if you didn't poke a hole through the monitor in a raging fit!) Although we all take them for granted, a lot of thought and engineering went into the development of the "ordinary" high-resolution optical mouse.
I think touch screens are perfect for 5"-6" cell phones, or even for media consumption devices like tablets, because these are portable devices deliberately designed to be small and portable. But for sit-down desktop computers with comfortably large monitors designed primarily for performance, work, and even play, where portability is of no importance at all, touchscreens make no sense. Pure lunacy, imo. I once had a very brief argument with a guy who kept insisting that sitting in front of a large, perpendicular monitor and constantly traversing it with arm/hand to push buttons and gadgets all day would be no different from using a mouse. He tried something like I suggest above and then I never heard from him again on the subject...
To this day I have no idea what Microsoft was thinking when it decided the next windows UI should be designed around touchscreens even for people who either didn't have, couldn't have, or didn't want touchscreens. Designing a touchscreen UI is OK--what's not OK is trying to force people to use a touch ui whether they like it or not.
I like Win8x64--and I can even truthfully say I like it better than Win7. But I also have to say it's because of 3rd-party freeware developers that I am able to use Win8x64 in the way that I like--with the Explorer UI, booting to desktop, etc--and not because of Microsoft. I'm aware that Microsoft is correcting some of these incredible mistakes in "8.1", but I'm confident the company will be stubborn enough not to get them all. I want the OS I buy and use to shape itself around me as opposed to me having to conform to some nebulous UI "touch-screenish" aesthetic whether I like it or not. That's something like I'd expect to see from Apple, frankly.