All of the examples given are discoverable, even with a mouse and keyboard IMHO - particularly given that all of the keyboard shortcuts (such as the Windows key for the start screen and Alt + F4 for closing an app) all still work.

The thing most desktop-oriented criticisms of Win8 overlook is that the overwhelming majority of computers that are going to ship with Win8 installed WILL HAVE TOUCH. Comparing the experience on an existing PC and extrapolating that to how the experience will feel on devices that are sold starting in October is Apples to Oranges.