[LukasMathis]

Then why don't these people use iPads? (Maybe because iPads are actually more complicated for most common work-related tasks.)

Your claim that only a minority of people use more than two applications needs a source, because I don't know a single person who gets by with just two applications for work. Pretty much everybody uses at least an email client/office messaging app, a browser, and Word, and those are just the generic tools; there are very few people who don't also use work-related, specialized tools.