Let's be reasonable... 3D games and traditional desktop environments have a very different set of HCI expectations. You aren't often clicking an icon in a 3D game.
While, I'd probably prefer to have vector graphics for desktop assets just for the flexibility, hand-tuned scaled images usually look better than their vector scaled siblings.
While, I'd probably prefer to have vector graphics for desktop assets just for the flexibility, hand-tuned scaled images usually look better than their vector scaled siblings.