Look, it's pretty simple. If Microsoft could make a version of Windows that wouldn't need to patched for several months on end, they would do it. Unfortunately, they can't. And for as long as software is written by humans, no one will be able to accomplish such a feat.

MS has insane security standards in place since the security push of XPSP2. This is literally as good as they can make it, and they're already at least as good, if not better, than anyone else. It's simply not possible to do better with current software engineering techniques.