The simple truth is that corporate users tend to be very cautious about upgrading (and who can blame your average IT department for its conservatism) and many individual users only upgrade when they buy a new PC.<p>In my feeling, by analogy, Windows 2000 was like when they first put modern electronic ignitions and truly reliable fuel injection in passenger cars (making a whole class of maintenance and problems a thing of the past). Now it's just like buying the latest boring mid-sized sedan with slightly different styling.<p>For me, Mac OS X, ten years ago, was like getting a Tesla. Desktop OSes have become such a commodity since then though.<p>As much as I don't like the iOS model and its restrictions and business model, it's probably the first serious innovation in "desktop" OS products in a while.