I think this is something we should definitely reconsider. I've been on Windows my entire life (I really hate change) and with Windows version specific software, there aren't that many that exist. Software for Windows usually depends on if you're using Windows XP specifically Service Pack 3 or later.
Unless a software is really specific (like this one: Tool to remove upgrade to Windows 10 prompt which ironically is just using the windows tag) - it doesn't matter. I haven't really come across any software that was compatible with one version of windows and not another (like at my school, their running on some PCs Windows XP and others Windows 7 while at home I'm running Windows 10. I use PortableApps & Cameyo and I have not seen one program that hasn't been compatible on any one of the three yet).
I think version specific tags are in a way useless and might add confusion to duplicate questions, ie. if I ask for a text editor that runs on XP and another person wants a text editor that runs on Vista, what's preventing from asking virtually the same question twice? And there going to get the same answers too.
Again, this is something I have quite a bit of experience in and I believe that they're not needed. What I propose is we remove of all version specific tags for Windows and replace them with the just the windows tag. I then think we should also add the requirement, "this software must be compatible with Windows X" in the body of the question.