In an interview with USA Today, John Carmack said he wanted Oculus Rift VR support in future id games like Doom 4. His plan was a partnership, a deal between Oculus and id owner Zenimax. But this wouldnt happened with Zenimax. So he left id in November 2013 to work fulltime at Oculus as Chief Technican.
"I would have been content probably staying there [id Software] working with the people and technology that I know and the work we were doing. But they [Oculus, Zenimax] couldn't come together on that which made me really sad. It was just unfortunate. When it became clear that I wasn't going to have the opportunity to do any work on VR while at id software, I decided to not renew my contract." (John Carmack)

Source: usatoday