Haha, that is exactly what I thought of when I read about this earlier today!
This is something that I've been thinking about for quite a while, and as awesome as it would be, there are plenty of limitations.
Ignoring the low FOV and other limitations of the VR unit itself, the major problem I see is HAND tracking. It's all well and good to be able to sit in a fully realized virtual pit, but how are you going to track your hands and fingers to activate the virtual switches and buttons?
If you had a physical cockpit that was laid out exactly as the sim, it would take some practice, but eventually you could hit the real controls without needing hand tracking. But that would limit you to flying only one type of craft.
However, if you were somehow able to interface something like a Kinect with the sim, AND the sim was able to display a 3D hand in virtual space, AND all the controls in the sim were fully realized and programmed with collision detection or something similar so that your virtual finger activated them instead of clipping through them, AND there was also some sort of haptic feedback to give you a physical sensation when the controls were activated... THEN I think it could work.
But if you just want to use it as a 3D display with head tracking in a more-or-less static cockpit in a sim that isn't all that complicated, well that's cool too.