It seems to me the oculus rift can accrately account for all head motion when you are standing still. There is no need for eye-tracking: All the rift has to do is detect all head bobbing & rotation, and update the view acocrdingly. Your eyes can still look around on the lcd screen.

What the rift _can't_ do is account for long term linear acceleration (eg in a car or walking around), it's true. If you had a large empty room to walk around in with the rift on, even this could be accounted for, however.