considering directx12 is really in a beta stage on pc i dont see it as a huge suprise that a console (even xbox one) is taking time to get the kinks worked out and running strong.
even at the first full year(2014) they would be releasing updates on a very regular basis.. so compund that with xbox ui updates,interface updates, and potentially directx12 it would be allot of cross engineering to get everything on the same page. heck the xb1 is on a 1-1.5 month update right now...
again directx12 is really only in a beta stage on pc as it sits right now.
http://www.gizmodo.com.au/2014/03/heres-what-you-need-to-know-about-directx-12/
View attachment 2768