The justification is that they feel it necessary to make obvious, superficial changes in pursuit of differentiation between software versions to help keep the upgrade treadmill running.
The only UI change that I've found useful since Yosemite was Mojave's introduction of a dark mode. They made the fonts look worse on non-Retina displays, threw out the Preference pane in favor of a weird list that can only be resized vertically, added transparent everything, and banned any icon that's not in a squircle. Such UI, many differentiation, much insanely great, wow!
The only UI change that I've found useful since Yosemite was Mojave's introduction of a dark mode. They made the fonts look worse on non-Retina displays, threw out the Preference pane in favor of a weird list that can only be resized vertically, added transparent everything, and banned any icon that's not in a squircle. Such UI, many differentiation, much insanely great, wow!
Anyway, I bought a ThinkPad.