I feel like as the computer literacy of the people making decisions in tech companies has gone up, the care that's being invested into actually making good user interfaces has gone down. This applies to Macs, Windows, and also to Linux desktop environments.
Just 15 years ago, there was a heavy focus on usability and making user interfaces clear and readable. Now, the focus seems to be much more on aesthetics. People used to care about making sure buttons are recognizable and differentiated with icons, colors, and clear labels. Now it's just text. People used to make sure windows had clear, visible borders, and the active window was clearly identifiable. Now it's just a shadow, and if you have a dark user interface, you can't even see the shadow. People used to make sure scrollable areas where clearly identifiable, now you have to just guess at what is scrollable.
From the screenshots, this looks like the same low-contrast, low-usability, but visually pretty design approach most modern desktop environments have adopted.
It's unfortunate that this seems to be the direction we're going in.