If they offered a new version of Windows 7 with more or less the same nice polished UI on new framework with all the latest security updates and several years of patching
That's what I mean: Windows is a solved problem. You don't want new features, they don't care about rewriting things that ain't broke, there is no business in it anymore besides maintenance. You don't really need new Windows, you want Windows 7 LTS. Many other users would even be happy with XP LTS.
Yeah. There's still a couple fixes I would like to see in Windows 7 (apart from potential security fixes): both with the file explorer. And that MS never cared to fix.
One is with file refresh. Many times, but somewhat randomly (at least, I can't find a pattern), the content of open, folders in the file explorer is not automatically updated when there is a change (file or directory modified/removed outside of the explorer, for instance). This used to work perfectly fine in older Windows versions. The problem is not just with distant directories of course. Files/directories on the network, I can understand why they can't be updated in near real-time. But with local files and folders? That's unbelievable. Often you have to manually refresh with F5. That's a well known bug, I had found a KB entry for it, but MS never fixed it.
The other is with folder view settings. Randomly, some folders will lose their view settings. The one I've seen this bug most often with is the "Devices and Printers" folder, but I've also very occasionally seen this with other folders. Sometimes the navigation bar will just disappear for no reason. Or the view type (List, Details, etc.) will change on its own. Most often occurs when you leave explorer windows open, shut down your computer and start it again, so this one may be linked to the option of saving open file explorer windows and restoring them upon reboot.
Of course, one can use a third-party file explorer instead. I've tried Explorer++, which is not too bad, but it's not quite right either and is of course a lot less integrated than the native explorer...