But they don't. They've cloned some superficial UX bits.

I'm still dismayed that in Windows 10 you still basically have 2 separate UI/UX experiences to configure the damn OS.

Isn't that incredible? Trillion dollar company cannot have a top-down decree that the mixed UIs need to be fixed for the next OS.

Yes, they cannot. Because the new UI is more or less useless and touches core functionality (i.e. interaction with HW). Maybe they were told by kernel engineers to not touch this part.

A couple of days ago I run into one of those windows in Task Scheduler. I had to type a long string of program arguments into a right aligned narrow text field (plenty of space at the left of it) inside a window that I could not resize to make that text input wider.

Luckily that was a VM in my Linux box (the luck is that I use Linux, not Windows.) The Linux equivalent would be either cron or systemd, which are configured with text files that I can type full screen if I care. Microsoft made a ton of work building those graphical UIs and in some case the result is worse than not doing it and using text files. Note that GUIs are not magical. To do what I was up to I still had to look for documentation and eventually had to type some XML in a text area. That is to start a task after another one completed.

I understand that OSs are really complicated. I've been exposed to every one now for almost four decades.

What's dismaying is that in that four decades it's now just regression. I admittedly have used MacOS for a couple of decades -- simple and it works well enough, but always run Windows as a secondary OS and Linux "as needed".

Windows has gotten so ersatz and bizarro that it's just strange to me when I do use it every few days.

Windows 2000 / Windows 98 had it down. It wasn't fancy, logical, and it worked. It's been a confusing mess since Windows 7.

Windows 7 was probably the best it's been for a long time.

But you're right, they completely screwed up the control panel. If not for that then it would've been the new pinnacle (let us never discuss Vista).