Anybody who tries just glitz without underlying value fails. Remember most PC users trying to pimp-up their PCs with plastic in the face of Apple's design successes? Remember Apple's own Mac Cube? It was very nice and glitzy, but it cost far more than equivalent Mac hardware. Not many people have that much money to shell out for looks.
I look at the G4 Cube as a step on the way to the Mac Mini. For years, a lot of folks were clamoring for a "headless iMac," so they could save some money by using the monitor they already had. The Cube wasn't it. The Mini was.
The Cube, the 20th Anniversary Mac, and (I would argue) the first iteration of the MacBook Air were what Apple-bashers claim all Macs are -- machines that charged a hefty premium for aesthetics. There is a limited market for such machines. On the other hand, machines with smart, functional, and yes, aesthetically appealing design, like the iMac, the MacBook Pro, and the current-generation MacBook Air, iPhone and iPad sell quite well.
I suspect that may also be somewhat responsible for the demise of the XServe. Nobody wants to pay a premium for a glitzy machine that spends it's life in a dark room.