No 360 version is millions left on the table for someone else. I don't get why people find it so strange that Microsoft want to make money. I mean really.
Don't like it sure, but it's pretty straight forward why it is this way.
Short term goals versus long term goals. Short term is to make as much money as you can, which is to get more versions out if affordable. Long term plan is to get people to adopt a new, potentially more lucrative product, and try to goat them into moving there. This could be taken as implication that they don't see the long term goal as viable anymore, OR that there's better games to use that long term goal for such as Halo 5. Now that's a game that'd cause uproars being cross gen, and really might be a dumb move in the long run.
Though I think there's still that underlying factor of whether a game can be scaled down well or not, and while an open world game it IS all about racing, not getting out of the car and shooting or beating people up. Even those could work on older hardware, but it seems the likes of Arkham Knight needed the extra power to get the Batmobile in, at least in a manner that doesn't compromise the rest of the game I assume. But at best this is Batmobile: the game, and Drivatars aside most everything else is probably visual updates.
