I can't help but think about what happened with graphics APIs - the older ones (DX9, OpenGL) held your hand more, and the new ones are super bare metal and not written for the faint of heart. I think most would agree this is better though; for an application developer you can simply use a much higher level library built on top, and for the library/engine developer you have a lot more power and control. The old APIs were in an awkward middle ground of not being particularly easy to use, but also not being nearly low level enough. Nobody was happy.
I think modern OS stacks are in a similar boat, at least Windows and macOS. True low level control is kind of a pain, but the OS libraries are not particularly pleasant or high level enough either. So largely things like Electron or Qt are acting as the defacto OS anyway to varying degrees of success but undeniable levels of resource waste. I wonder if modern languages and tooling and such are advanced enough that the OS should become more primitive and minimal. In a way it feels like we're moving there anyway with web tech becoming the defacto user space and toolkit. That's fine, but god if it wasnt all built on 50 layer of cruft our machines would be screaming fast.
Smalltalk, if you get a chance to use it, really does act like its own OS in so many ways. It's great as a programmers OS really, although it doesn't really hit the right notes for average use. Still though, if someone had the urge to build it I could easily see a smalltalk based userland built on like a linux kernel (with no gnu user space) being a totally viable thing.
Nah, Android, macOS and Windows are doing just fine, it is the classical UNIX desktop that cannot get their act together.
The existing issues aren't technical, rather political, like the WinRT crusade that ended up bombing and now we have plenty of GUI toolkits to chose from on Windows.
Swift, Java, Kotlin and the .NET languages are more than high level enough.
MS .NET burned me hard with WPF. After finally looking into it, it more or less was cancelled for greener pastures.
I don't think the newer Windows UI-Frameworks are loved that much and UWP is not really convincing for desktop applications. Just too much hassle for too little gain and the threat of vendor lock-in.
But yeah, having ramped down the team while beting the farm into WinRT wasn't the best idea.
Still, just like VB 6 in Windows 10, WPF will be around for decades to come and it isn't like there are revolutionary UI concepts to implement.