I'd prefer not integrating Steam too much, since this is a shared computer that my kids also use.
I do like the UI of big picture mode, so if there were something similar that could be used by a remote or controller, that'd be top tier. Steam games could be added in via shortcuts
I just bought a Sony BRAVIA 8 and it's close to this. Never connected to WiFi. It goes directly to my HTPC input and I never see the home screen unless I want to.
Functionally, it's the right thing I'm looking for, but it's not polished enough to fulfill my needs.
If this allowed folders and a GUI for settings, I think it'd be a winner.