Wolfgang, that one is EASY... but you must think a little 'differently' that just a single system. One word, SUPPORT, or SERVICE, if you prefer. Yeah, the s/w operates differently on different h/w, but the code would be the same base, maybe with some IFDEF's for compiling and IF statement for h/w or s/w version, but the base OS would be the same. Fix a file system problem once and done. Adding a 'new' feature, like Blue will, code once and done, vs. updating a few sets of source code. Usual problem is what does get fixed in one set of source code and then gets 'duplicated' in another set, doesn't work as that 2nd set had either slightly different code or something elsewhere that didn't work with the change.
That said, it would have been just as easy (Stardock knows how) to check if on a non-RT unit and if so, bypass the Start Screen... so you put down some extra code, who cares? Or make it an OPTION on install.
Although I boot to the Metro Start Screen I *RARELY* use anything there. Generally if at all I'd look at the stocks, news, sports, and not much else. I don't even LOOK for icons that were put there by program installs. First thing I do is click on the DESKTOP Live Tile and usually never go back. Created REBOOT and SHUTDOWN icons on my desktop and use those. I'm quite happy with STARTMENUX and use it like the old W7 Start Orb.
Like I said, other than some 'annoyances', like some h/w issues or where things have moved to in settings, I wouldn't know I was on W8.
Many Geeks WILL move because generally speaking, they ARE first adopter's and like to be living on the 'bleeding edge' of Technology. It is the ones with limited technical knowledge or motivation that will not move. Of course there are also those that are resistant to change too that will not change.
One thing going against W8 inroads to the install base. Computers today are not moving forward like they used too. My 'cutting' edge almost 4 year old system is FAST ENOUGH by today's standards. No new apps that require gobs of storage or speed have appeared. Not like 5 years (or so) ago where MS Flight Simulator X was released and most systems didn't have the CPU or Graphics capability to get full features out of it. Today that isn't the case, almost any new computer will do well, if not be equipped for full display and smooth speed for the program.
Even First Person shooters are no longer h/w restrained by today's computers, but more about network speed and lag.