Full OSes don't work on tablets
It's more than a touch-vs-mouse debate. The operating paradigm of a tablet OS is different than that of a desktop OS. Tablets are meant for immediacy and long battery life. Both of these things require that the software work within the constraints -- things like near-zero load time; not having to reboot; *very* little processing in the background; one-app-at-a-time multitasking and data sharing; interaction timeout; interruption by foreground alerts (think phone calls and texts on equipped devices).
Windows 7-style OSes don't and haven't done these things, and it takes more than a new OS release to shift the applications away from the model they currently use to one designed for mobile platforms.
Otherwise, it's just a laptop that you hold like a tablet, with all the baggage of the current crop of hardware. Windows 8 won't (can't) change that. So, Justin's already covered that by not giving up on traditional desktop applications. He's merely focused this article on the tablet / mobile *software* side, regardless of what form factor the hardware comes in.