Apparently to Apple the aesthetics is the number one priority. Otherwise https://www.apple.com/macos/big-sur/ wouldn't be mostly about new UI bringing even more "magic". But it is. So it is Apple who creates such priorities, not us. So please don't be surprised that people are discussing it, as by the way there is not much to be discussed besides that. And please stop bashing people for discussing UI, in the end it is what you see for many hours of your everyday life.
I wish Apple had different priorities though and would not be putting most of its software engineering resources to redoing UI all over again every freaking 2-3 years. There was absolutely nothing wrong with the Catalina UI. But Apple is money driven corporation and it looks like (at least for Apple's marketing and sales) that doing UI that looks nice on screenshots is what sells and what makes a reason to call BigSur new major macOS release.
Times when Apple was talking about new technologies like when Snow Leopard came out (e.g. OpenCL, GCD) are far gone. Only M1 is exceptional, as it is really a new quality in terms of the CPU performance, but besides that, Apple is IMHO hardly innovative these days.
every new apple OS has a lot of work under-the-hood; and there are huge leaps sometimes (moving to an exclusive 64bit architecture, for example). i think you're completely missing this. meanwhile, if apple wants to update the GUI with each new OS, that's their right, it's their OS.