I don't know why the X1 wouldn't have a bigger following as IMO 360 killed everyone last generation?
1) They pissed off alot of people. Even reversing the changes, for now, people have seen the pay per view direction that MS wants to take gaming.
2) 360 dominated early on because Sony royally screwed the PS3 launch, yet despite that, came back to tie or even beat MS last generation. This time, so far, Sony did everything right out of the gate instead of catching up for 2+ years.
3) Its $100 more.
4) Its a week late.
5) Its not 1080p (or some games lower res than PS4) = "inferior" multi platform
6) Halo/GoW/CoD fatigue. These were new and groundbreaking 8 years ago...not so much now.
7) NSA, Kinect, etc conspiracy theories
Some of them are completely stupid, but these are legit reasons there MAY be less demand.
On the plus side, I see everyone who didn't get a PS4 getting an XBO just to have something.
Personally doubt it won't sell out too. There are enough NFL/UFC/Halo/CoD types who will just have to have it.