It's all mostly redesign for the sake for redesign at this point. Desktop OSes had been feature-complete for quite some time, but they still have to update every year. They have to. Don't you even dare question that. I'm still on Mojave and it does everything I need from an OS. I also absolutely love native Mac apps, which are becoming rarer and rarer. And no, iOS apps that run on macOS aren't native mac apps. The abomination that is the mojave app store? That definitely took some extra talent to break every single UI guideline, but thankfully I only open it once a couple months.
Just a thought: If someone in 2008 asked me -What desktop interfaces will be used in 2020? My answer may have been: Apple will implement a new Desktop paradigm on top of Raskin Zoomable UI Ideas (https://en.wikipedia.org/wiki/Jef_Raskin).
But here we are: Monster SOC with Cartoon Network on top. :)
The thing with interfaces is that there's no inherent need for change if the method of interaction doesn't change. It was a non-touch screen, a keyboard, and a mouse/trackpad 20 years ago, and it still is today. Some things just work great. They're tried and true and battle-tested. Like, you know, densely packed windows that are optimized for the precision of the mouse pointer.
