My intention is to populate the first column with applications that would be useful for a HTPC, such as the three apps I mentioned and also weather, news, and anything else that I find useful (maybe some games, or Netflix Metro)
I'm afraid I don't understand this statement. I would be basically using Metro Home as a replacement to having WMC on. Each application would be acting like a WMC/XBMC category (Movies, TV Shows, Pictures), and none of these things are organized in folders. Heck, WMC's subcategory system is crap, as I had to use MCS to strip out everything That I don't use or can't use (such as radio and TV Shows, since I don't have a tuner).Metro might make a tiny amount of sense for HTPC purposes if Metro tiles were nested like folders are. As it stands right now, sure, you could have a bunch of unrelated apps "unified" in a weak sense by the Metro start screen, but they would appear in a sea of apps that have no business being presented alongside programs designed for a 10' interface.
Additionally, Metro is very modular, and Microsoft is pushing it as the default interface. In case you havent checked, neither XBMC not WMC have perfect plugins. XBMC doesn't properly work with Blurays, and WMC doesn't have a single Weather app that is not boggy, ugly, or doesn't have my town (and the latter is impossible to uninstall)
With metro, I can have front and center access to my picture library, Music, movies and TV Shows (assuming MB does come and allows for separate applications), disk playback, internet, and any media streaming applications I find. And it wil be easy to access and no risk of accidentally dropping to the desktop, Which is good because this will be a central computer that everyone can use to watch movies and stuff.
And like I said: I'd love to do this, but it needs certain applications that currently don't exist.