Whats the purpose to mark certain NPCs as essentinal?

[Raijin]

One particular NPC that I have in mind is Rolff Stone-Fist. He serves no real purpose in the game other than to be an asshole to a dark elf. You're unable to kill him because hes marked down as an essential. Can someone give me a logical explanation why was marked down as an essential, but merchants like Adrianne Avenicci and Ulfberth War-Bear of Whiterun can be easily killed during a vampire raid (If you have Dawnguard installed)?

Also after you finish with the civil war and raid Stormcloak/Imperial camp sights out in the wilderness all but the legate/Stormblade can be killed.

 

[neonworm]

Some npcs are marked as essential so you don't kill someone that is part of a quest and you won't be able to finish the quest.

 

[Medea]

One particular NPC that I have in mind is Rolff Stone-Fist. He serves no real purpose in the game other than to be an asshole to a dark elf. You're unable to kill him because hes marked down as an essential. Can someone give me a logical explanation why was marked down as an essential, but merchants like Adrianne Avenicci and Ulfberth War-Bear of Whiterun can be easily killed during a vampire raid (If you have Dawnguard installed)?.

So you can beat him down over and over again.

 

[Janus3003]

That's one thing I like about Morrowind- no essential characters, just a "YOU'VE DOOMED THE WORLD!" message when you kill a main quest important NPC.
And from what I hear, you can still beat the main quest through another method .

 

[samgurl775]

To really annoy us. Bravo on a job well done Bethesda.

 

[ThriceHeart]

I had found the Stormblades to be quite annoying considering that they can't be killed but everyone else in the camp can be killed but my guess is so they can look after the injured warriors in the tents, considering that they would be easy prey for the Imperial soldiers. But now that I have found out that Roliff can't be killed I might just go and give him a "Shocking" surprise visit.​