Ah, yeah, I can see how if you had worked with the 9x theme for 10 years you'd prefer it didn't change. (Conversely I don't think anyone is clamoring for the 3.1 theme back) But XP did include that theme and it was pretty simple to select it.
It was directional and trendy - which meant it was short lasting. Like building your UI based on floaty 3D shapes 5 years ago, except these days it's much easier to change when you start to look silly.