Judging from the prevalence of fingerprints on many monitors, your 3' distance seems to be larger than average.
I prefer to keep electromagnetic radiation exposure at minimum levels, when possible.
I agree that a "touch-only" system would be tiring.
As would be for any vertically mounted multi-touch screen, while seated in a chair.
However, touch as another available input paradigm in addition to keyboard/mouse is very handy. Poking the "submit" button on a web page is quicker and more natural than
1. Find your mouse
Never lost it - the mouse remains under my hand while working with graphics, sound editing, movie editing, or submitting info on the web. After typing, the mouse remains kinesthetically
at a much shorter distance than any random locations on the monitor, a surface which I prefer to keep free of finger prints and smudges.
2. Move the mouse so that you can find the cursor
Not that much of an issue, being that the table top functions as a virtual monitor while using a mouse. This will soon be the case for the muti-touch mouse itself, whereby one
will be able to move the curser via scrolling gestures. Besides, I'm more willing to utilize a multi-touch mouse as a virtual monitor for selecting buttons in favor of exerting the extra
energy necessary for lifting up and reaching out with the full arm, against gravity, to hunt and peck at random places on the surface of the monitor, all the while lacing it with fingerprints.
3. Move the cursor over the "submit" button
It sure is nice not having to lift my arm, away from the keyboard and mouse, to reach up and out for buttons.
4. Press the mouse in the correct way to register an MB1 event
In the end, the mouse solution requires far less energy exertion. At the end of the day, the time and effort saved, in not having to thoroughly Windex a 30" Cinema Display,
is well worth bypassing the need to reach up and poke a monitor. The cinema display happens to be a matte screen - cleaning it on a daily basis would be a RPITA.