Ooook, so, history lesson: Casual players complain Coil is too hard and they're getting left out of the story. Yoshida listens to those players and releases a "dumbed down" version of the same fight so casuals can get their story while raiders can get their raid fight and loot with Savage. Savage IS designed as the same fight with updated mechanics and harder heal/dps/tank checks (then players suck and demand these be dumbed down as well...).

In short: we already have Savage so a greater number of players can clear the side story content and maybe get an interest in raiding. If you really don't wanna have the fight "spoiled" just get a group to carry your body thru normal, it's not like the fights are hard, anyway.