I think some people who use computers daily find that there is something kind of monotonous about them. They're always the same, day in day out. Once you've got used to the quirks of your machine (which you need to do to be productive) there are no surprises anymore.
People who work in the big blue-ceilinged room however (in many places) have weather and seasons to deal with. I suspect the variation helps their job satisfaction.
Suppose one wrote an application for giving computers some equivalent of weather. It would subtly modify the desktop theme on a day-to-day basis (sometimes even more often), changing colours slightly, modifying the screen brightness, perhaps adding rain or snow effects in the background. Nothing that gets in the way of what you're doing too much, it just adds a little unpredictability and variation to ones day. I suspect such an application could be quite popular if done well.