Therefore I was surprised when I actually started Blend under Windows 7. I got slapped with "... supports only Windows Store app development on Windows 8 ...".
Under assumption that there is some programming API for retrieving actual version of Windows, I cannot think of an excuse other then pure laziness why this item ended up offered as instalaltion option. If you know that your component does not work under certain OS, do not even show it to user. And do not even think about actually installing it.
I understand that Microsoft wants to sweeten deal for early Windows 8 adopters. I find nothing wrong with that. It is actually really sensible thing to do.
But do not install by default stuff that developer cannot use. It will just make him cranky.
P.S. Uninstalling Blend left it's item and project templates directories behind...