My fear for Dx12 is that it is going to be windows 8 only, for arbitrary reasons. Microsoft will think it's a great way to monetize the development. But they'll actually delay market penetration because every game would still need to support windows 7 through dx11 for several more years.

If they are smart, they'll release it as a windows 7 / windows 8 "service pack", but require the user to authenticate online first. It'll still hurt acceptance, but it's much harder for the player to argue "I pirated win7, it should still work" rather than "I bought win7 18 months ago, now it's useless". Unfortunately, MS are hell-bent on phasing out win7 as soon as possible.

I can't say how much I hate the Windows 8, and how its UI has ruined the charm of the PC. Thankfully Stardock has some good programs I can use to fix that problem if I some day should be forced to use this new Windows crap.

The reasons are quite reasonable. Mainstream support for Windows 7 ends January 13, 2015. After that only security fixes for 5 years. They won't release a major feature couple months before support for the OS ends.

That's not a reason for how they decide to act. That is how they decide to act. Now they need a reason for it. And as I said, choosing to make it win8 only will mean devs won't be able to adopt dx12 as quickly. Because game devs sell games to people who mostly do not use win8.

So, devs have no reason to support only win8. This means microsoft has no reason to only support win8.

 If you are not swayed by my argument, consider if you will the fact that only this year are "64-bit only" major games starting to hit the market.

Windows 8's market share has ben declining steadily since December (source: statcounter). Windows 7 is refusing to drop.

I don't know whose brilliant idea it was to put a gesture-based OS on a mouse-based platform, but Microsoft is going to need to up its game or else create an ever-larger oppourtunity for competitors.