Battlefield as well, but similarly some of the PS4s flagship games (Infamous) have had issues reaching 1080p @ 60fps so it's really not an XBox One only issue contrary to the claim above - that's really just popular myth spread by fanboys and peddled by the unaware. I suspect above all else it's simply because both consoles are new hardware.
The real test will be what's going on in a year or two, if there is still disparity then then there is a problem. Judging current titles is difficult because the hardware was still changing when all current titles were in development so current games were all developed against a moving target and that's bound to cause issues by the time release is reached. This is especially the case with the XBox One where Microsoft completely and utterly changed the DRM system and so forth last minute which will have required effort by devs - effort that could've meant time that would otherwise have gone towards better optimisation.
Microsoft recently lowered the requirements on reserved CPU for Kinect, so I imagine that had some relevance too - they were perhaps just asking developers to put more aside than was necessary because they weren't sure themselves what they could get away with. Both companies are still refining their systems, but too a lesser degree. But again, it's only Christmas next year (Christmas 2015) that we'll begin to see games developed purely on the now static hardware definitions and many not even until Christmas 2016 as a 3 year dev cycle for an AAA title is fairly typical.
If last generation is anything to go by though I suspect in a year or twos time it just wont matter anyway - games will almost entirely be getting ported to both systems, exclusives will be rare, and it'll only really come down to whose controllers and interface you like best at the end of the day.