To kill or not to kill innocent NPCs?

Today I've been watching an old video where Chris Crawford was talking at 1992 GDC (the famous dragon speech) and it motivates me to dig deeper into his activity. He is now trying to raise money for his project Siboot and watching his presentation I had an idea: Why not give the player the ability to kill everything that moves? Friend or foe, villain or innocent alike. Would this option motivate the player to be more responsible in his/her actions? I mean if you kill an NPC that is later a chain link in the main quest, then the game will be broken and you will not be able to complete the game. Of course, I provide means to overcome this situation:

1. restart the game, probably used only when the user is at the beginning of the game;
2. buy a resurrection scroll (real money);
3. redeem the soul of the NPC by going to the underworld, a new level where you have to kill hordes of enemies before getting back NPC soul.

For me, as developer the second variant is most appealing. But maybe implementing all 3 variants will be the right answer. What do you think? I would like to hear your opinion here

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