Because xbox is seen as the lesser platform. I have both systems and really there are better games for ps4...and the system is better overall. Other than Halo there is not much else to play on xbone. Sunset overdrive? That is for kids. Forza Horizon 2? Played the same game on xbox360 when the first game came out. Titanfall? Worse story than Destiny's. Really. Out of the two I find myself playing ps4 all the time. There are also more ps4 users overall I think. No wonder Bungie prefers ps4 over xbone.