In the case of Crackdown 3, it's an online game so no increased costs. Crackdown 3's importance is to show that complex worlds can be structured such that their data can be sync'd over the internet. The showcase was thousands of 3D objects being updated, but that was only ever demonstrated over a LAN AFAIK. Crackdown 3 working over the internet would be significant, but perhaps the reason for the delays is it just doesn't work the way they hoped?