Microsoft killed the start button because it wasn't used

I suggest it's not so much reducing the number of Home/Pro/Enterprise versions that is the issue here. Historically, MS have had standard Windows and they have had Windows CE, Windows Mobile et al on the mobile side. Despite the similarity of names, the mobile versions have not really been Windows at all. With Windows 8 and Windows RT you have pretty much the same thing from a developer's point of view, and that very much is the key. Think about it. If developers can now develop a single application that works on desktops/laptops, tablets and smartphones you have a whole different ball game. If the vast array of applications that are available for desktops/laptops also becomes available for mobile devices, it changes the whole market. Windows-based tablets and smartphones will (eventually) offer the user much more than Apple or Android ever will. Rather than mourn the loss of your trusty Start button, ask yourself if you would you be prepared to give up the Start button (and a few other things) for that in return.

If MS are to achieve that common (application) platform, they have to make changes. And, I suggest, they have to make the changes in a way that is not optional. Give people the choice of the new way or the old way, and lots of people will stick with the old way, and that prevents the application market from burgeoning. Force the necessary changes on people and enough of them will adapt, and from that we all benefit.