And also the pen! Especially when I'm on a plane in a cramped space, the mouse is not an option; rather, I turn to the pen.
I've gone on record numerous times for stating that I'm sold on the Modern UI and, slowly but surely, I continue to migrate to Modern UI apps. As soon as I find the Modern UI version (or functionally-equivalent alternative), I make the switch.
I find that some people just need to stop, think, and assess the state of the Windows world rationally. Let's say that even if Windows 8 and the MUI were runaway successes and there was 100% instant adoption, Desktop apps would still dominate; that balance isn't and wouldn't change overnight because we've had 30 years of Desktop UI apps. It's unrealistic to expect MUI apps to be the dominant type of apps in the near- or short-time; it will take a lot of time. Moreover, it should not be forgotten that some apps are most effectively- and productively-used with a keyboard/mouse; thus, rewriting them to be touch-centric would be counterproductive.
Those who purchase a Surface Pro (or any other touchscreen Windows type of PC, for that matter) should not expect the ability to abandon their Desktop apps overnight; this transition will take lots of time, so no need for the constant criticism regarding the number of apps in the Windows Store.
On the other hand, if you do want to transition overnight and use Modern UI apps exclusively, then buy the regular Surface device. Then it will be fair game for you to constantly complain about the number of apps in the Windows Store.