New Mac desktops are shipping without DVD drives already. They led the way on systems without floppy drives as well.
Gives it a few years, and I think 95% of new desktops won't have optical drives. At least in those parts of the world that have decent internet connections.
While that may true Windows 8 doesn't provide the same value for those buying PC's today (desktop or laptop) with DVD drives today. This certainly isn't the biggest issue with Windows 8 but it certainly is one of its "thousand little cuts" that IMO slows adoption at worst or provides for disappointment for some. I'd think there was some room for "understanding" if there was something amazing in Windows 8 for desktop and/or non-touch laptop users but IMO there's not.