User blog comment:Madman97/You know what really grinds my Wabbajack's? S3E1: I can't kill these guys/@comment-25109952-20131025182427/@comment-1600847-20131107210217

Actually, what I said was that if essential NPCs become killable they usually do get killed. I used the mod example in my earlier comments to demonstrate what happens when they become killable.

Yes, I agree that "protected" would be the best system. However, I also point out that this can lead to problems since the game has bugged before and killed "protected" NPCs anyways. Whereas I have never seen an "essential" NPC turn up dead. If Bethesda could patch these bugs, then it'd be the best system. But for them it's much easier to just set them as "essential". No chance of bugs that way. Lazy, as I said.