part of any story lines, where their death might be possible?

So a dragon flies over riverwood, i head down there from the mines(looking to turn some iron ore into gold ore), and the inn keeper and the blacksmith are both dead.

So, now, we have 2 stores/shops that are completely useless, other than stealing from.

And it's been 2 months, in game, no one has taken it over.

everyone should be killable, but much much much much much much much much much much much (ad infinium) less stupid, maybe give them radiant AI again, as-is a pesant will charge a dragon wil an iron dagger but a guard will run screaming like a baby if i get attacked by a mud crab and wander near-by

I would prefer it if everyone was killable, but important NPC's like shopkeeps or questgivers only killable by the player.

I agree with this, I hate everyone being invincible.

Yeah, that's one of the areas where BGS screwed up. I agree.

o_O I've never even thought about this. This is the answer to all the problems I've had with the concept of Essential NPCs. So simple. Is there a mod for this already?

This. Hopefully Bethesda will implement this sometime.

I think the NPCs should just go into kneel mode (like all of your companions do)
This means that they wont be attacked once their life gets low enough, and wont get up until its recovered to an acceptable level.
That's why companions almost never die unless you do it yourself. Everything drops them as a target when that happens.

If you want all NPCs to be killable then you should be in favor of NPC dying because of any reason. I hate that line of thinking that only the player should be able to kill essential npcs. If they can die then they should be able to die like any other creature. If they run up to a dragon with their iron dagger then they deserve to die. I am in favor of making them MUCH smarter, but they should be able to die at the hands of any game character that can kill another game character. Villagers should run inside when dragons come. If a bear wanders into town and a shopkeeper can't run away fast enough then that shopkeeper should die.

If you want to make all NPCs killable then don't tenderfoot around by only making them killable by the player. It's all or nothing.