The first time I ran Rabanastre, I watched the cutscene before the final boss. It's about thirty seconds long, maybe. The alliance pulled the boss and locked the fight before I finished, so I never got to participate in that battle. That's one reason not to watch.

Second reason is that one party member said "watch cutscenes in your inn on your own time, don't waste MY time" before leaving. Over thirty seconds. THIRTY SECONDS. These people exist.

I can see why some people skip cutscenes rather than dealing with this.