If the 360 version is made by a completely different developer then who knows how it will turn out, the experience might be entirely different from the Xbox One version (which so far seems to be the case as they've said next to nothing on it except that they're aiming for experience parity)
When I say graphics aren't important, it means they're not absolutely vital to playing the game. That doesn't mean better graphics is somehow a bad thing. If all that was different between two games was graphics then I'd choose the better looking one. But when you compare things like a PS4 version of Battlefield vs Xbox there's more at play than just graphics. You're also choosing which controller to play the game on as well as which community or maybe cool features like head tracking/leaning with the Kinect.
So the ultimate point that you can't seem to get is that yes, graphics matter, but they're nowhere near the most important thing and in many cases there are other factors that determine which system to buy a game than just how many pixels are on screen.
"No control beyond these skies" GT: RollnThunder213