I feel like this is an oversight. I don't care a whole lot about the resolution itself - more what it implies. Microsoft talked up balance and whatnot, but the resolution and framerate differences make it very clear the hardware is significantly different. The resolution maybe the only difference now, but later that may mean better effects, antialiasing, etc at the same resolution (ie when both do 720p or 1080p in the same game, one will have much more power per pixel). Let alone first party games.
Yes, optimizing around the eSRAM may be a factor, but the ROPs, TMUs, compute units all speak for themselves.
And oh, before anyone else is confused, that sharpness you see in the XBO version? That's actually from reduced RGB range in the game which will be fixed shortly, it may look poppier but it's actually crushing blacks (dark grey becomes total black), so despite looking punchier it's actually only removing detail.