Computers Don't Listen
It's the old adage of the technophobe and we usually dismiss it as foolishness. Let's be fair - they couldn't tell a JPEG from a dongle. But they're right - computers don't listen. They always seem to be doing something more important than listening to you, the nominal user.
The reason is a major design flaw in all operating systems - they give too much priority to doing things quickly. For example, if I'm moving twelve million files from a floppy disc to my hard drive, the computer might be a little slow, as a matter of course. But why need this be so? I, for one, would prefer if the computer paused doing that for a second in order to move the mouse pointer when I tell it to.
Computers should be programmed so that the top priority is responding to the user. I don't mind if a “working” indicator has to be substituted for genuine progress - at least the computer would seem to be responding. When I move the mouse, the computer should drop everything in order to comply with my instructions. It should ensure that my music continues to play smoothly, then that the visualiser displays smoothly. Then if there's spare processor power - and only then - should it go about completing background operations like file moves.