To be fair, so are many other UIs. Windows 95-style boxy buttons and bevels make the content look organized. Every possible action gets its button that looks like a button. You often see the total set of available actions by looking at a toolbar. You don't need to second-guess whether some piece of content itself is clickable / editable or not.

Also, everything has excessive padding now. Modern Windows control panel UIs often feel like a multicolumn wall of text with lots of empty space and a few switches dropped in, and to fit the same amount if options as the older UI they had to either hide some toggles because "known needs them anymore" or introduce extra intermediary navigation steps. As a result the new Control Panel feels bloated and less useful.

Funnily enough when Aqua was new i remember thinking Platinum looked so much better.