I'm always wondering whether my preference for this more "traditional" design paradigm just comes from using Win32 in my formative years or some objective difference of quality.
Anyone who shares the sentiment might want to check out the Chicago95 theme[1].
There is also a Twitter thread that notes what got lost over time - especially separation and contrast. https://twitter.com/tuomassalo/status/978717292023500805
Back when ads were actually a different background color on Google, I suspect they A/B tested background colors right up to the point that they disappeared on cheap TN laptops. I experienced this first hand when helping a friend with their laptop 5-10 years ago, and they clicked on an ad by mistake. Turned out that the ad background turned white at normal laptop viewing angles.