They probably cut out loads of stuff after the development nightmare. I suspect much of the plot was removed from the point where the party goes to Gran Pulse. That felt like a mid game point and then we ended up with "We can do it!" repetitions for the second half instead of anything meaningful. For a game that was supposed to focus on story, the story felt really half baked and incomplete.
Interestingly, I remember reading that Serah was also supposed to be a playable character. But constraints couldn't make it happen. Seems to tell me a lot of the plot was changed due to mishaps.