I suspect a lot of this OS controversy is related to personal experience. I have been running Windows 7 at home, and Windows 8/8.1 at work, since they were released, and have never had any performance, application, or accessibility issues with either one. I use a large variety of applications, including older and newer games (only at home, of course ).
That being said, I have a friend who has never not had an issue with any release of Windows. I can't pinpoint the differences in our environments that would give us such widely different experiences with the same OSes, but something is causing him to have such a bad experience.
I have also worked in large corporate IT environments for most of my career, and have seem the same range of experiences with users, where some have no issues at all, and some have horrible experiences, and this is in an extremely homogeneous environment where everyone is running the same base hardware and application set.
Arguing about which OS is better or worse based on personal experience has to be tempered with the fact that we all run in different environments, and no one's experience will ever be the same as someone else's, no matter what OS you're running.
I would use Linux for everything, if i could, but Linux isn't perfect. Neither is Windows (XP, 7, 8) or OSX. CPM was perfect though. No viruses!
The fact is that people do still run on XP, and if you want to make as much money as possible, you need to be able to offer games to those users. These arguments shouldn't be about who runs what OS and which one is best. It should be about how we can best support the user base that's out there.