The reason why they fight (SPOILER)Orphan is better explained in the official guide (which I own). Basically (SPOILER) they didn't fight him because their focus said so, but to free the people of Cocoon from the fal'Cie. All of them. Including Orphan. Now Cocoon is free to start again, without the fal'Cie. It's basically freeing Ivalice from the Occuria all over again.