Until the Consumer Preview, it didn't strike me so much that Windows 8 was very touch oriented. I regarded the Start Screen as a complement to the Desktop, it has large icons of items you need and items you don't need so much. It was easily accessible, Windows 8 adapted to the mouse and keyboard fairly well, though not polished.
The Consumer Preview made it more touch oriented and segregated a complement to the Desktop as a totally different UI that could work together. It's a little odd to use the Charms bar, especially on Start Screen. One would figure the apps from the Windows Store would adapt to a mouse and make it less larger, but that isn't happening.
I'm not going to rag on Windows 8 as a touch ONLY operating system when it isn't. A touch only OS would be iOS or android. They don't have a Desktop like Windows 8. Honestly, that's what will make Windows 8 the best touch OS and mouse OS, it's the power of a PC at a touch, or a click.