Hi bastian74
My understanding is that a lot of work was put into developing VR for X-Plane through Oculus Rift, then a revised SDK came out that invalidated almost all of that work. Such is the life when developing for beta projects! However, many more bumps came up in the process and further development has been put on hold.
X-Plane is a small team and we believe that our limited time and resources could be better spent improving other parts of the sim that you would see more immediate benefit from. There are many hurdles to developing for VR at this time.