This is incredibly disappointing news, and a spit in the face to everyone who supports Codemasters and the Dirt Rally series.
If the Oculus API isn't going to be supported in the Steam version, the right thing to do would be to provide folks who purchased the game with an Oculus Key. Knowind Codies' history, I doubt that will happen.
Shame it's too late for me to refund the game - the only reason a lot of people bought it was the promise of VR support.