Windows 2000 was the peak of Windows UI. While features and functionality has improved in many ways, everything UI change since then has been a step backward.

Microsoft (and IBM and others) did a ton of good HCI research in the 70s and 80s, and used that research to make better UI for their operating systems. But sometime around the mid-90s when high-color displays started becoming the norm, UI experts started gradually being replaced by art-school types, and now it seems very little consideration is given to actual UI functionality, and the driver is entirely some bizarre sense of style from people who don't know anything about Human Computer Interaction, but seem to think no more deeply than "less is more".

These UI elements had reasons to look and act the way they did. This communicated information to the user (even if the user didn't realize it), and made software much more predictable and discoverable, and ultimately, more intuitive.