It's pretty obvious why.
Consoles have used the tactic of exclusive titles to entice users to their platforms for years now.
Unless the game is a massive draw however I feel it's usually viewed as a cynical or negative tactic which may deter users.
I'm personally not a fan of the way Oculus is doing business at the moment. I feel that as long as the hardware performance is similar, users will be drawn toward the more open approach of other platforms.
- Horsey