Nor are you a night elf when you do the War of Thorns quests. You are just as much a third party(granted a third party that can act) while doing those quests. We are considered adventurers for a reason. Also, saying you cannot feels as intense a feeling is folly considering to this day Arthas’ fall is still considered to be one of the most memorable pieces of gaming lore.
Hell, even the Wrathgate is considered by many to be one of the most impactful event of Warcraft and in that particular event you are literally a passive observer.