...and in this case, it's likely 90% DirectX. It's not showing an application with Metro design. If you include sample apps for a new development/GUI framework, then should show it off - this is the equivalent of showing off Metro by launching a video through the start screen.
I don't think the goal was to show off Metro as much to show how to use it and some practices they've learned along the way. Sinofsky was very clear that these are not shipping apps. He said it like three times to hammer it home. And then hammered it home that interns built these. He's setting expectations. At the same time, the fact that you haven't seen any real Metro apps means you'll see them closer to launch. I think there' s decent chance we're going to get Office:Metro at launch.