At first, I wondered the same thing. But I'm starting to realize that WP7 (and thus WP8) and Surface RT are completely different operating systems. I originally thought Surface RT would be like a tablet version of WP8, but it has become apparent that it's really just a slightly watered down Windows 8.
They took some elements from Windows Phone 7 for Windows 8, but many of the smartphone features are missing (Tellme, for instance). It looks like they just consolidated the "Me" hub into the People hub for the sake of simplicity, though I definitely preferred them separated.