So they had it for a while, and actually did try, and still couldn't get it. That doesn't sound good....
That's my thought. It's not a last minute thing that can be fixed and patched as some hoped. It's more of a long term optimization thing.
They haven't of course as you know, but neither have the game graphical features, if both consoles continue to improve and developers add more and more effects, then we're likely still going to be sub-1080 on XB1, though the games will be prettier than this first round, they may not be higher resolution.
That would mirror this generation. Where resolution did not necessarily increase as we went on, but effects and visual quality did. In some cases resolution went down or even dynamic, but the ultimate game ended up looking better.