It is part of larian's design philosophy, what they call N+2. Quests will have the "intended" solution, a fallback solution if the player does X (be it kill someone important or sell something they needed) and a second fallback for D:OS 2 if another player completes part of the quest in a competitive environment.
Allowing players to kill anyone gives them freedom to play how they want. This will be particularly important in D:OS 2 with potential PvP questing, as you can kill the NPC player 2 is trying to help, to accomplish your goals. It is more organic and immersive to not put arbatry limits on who can be attacked. The only limit is are you strong enough.
The problem is that it points to a design philosophy fundamentally structured around violence. I can't kiss anyone I want, so why should I be able to stab anyone I want?
There are plenty of limitations to what we can do and I think it's odd to say it's necessary to be allowed to be a psychopath and kill an entire peaceful village. I like the style of RPGs where you consistently can't attack NPCs. (But you may be able to provoke combat in dialogue.)
It bugs me a little how the game assumes you want to be a psychopath. Like I'm in a battle where one of my companions has high fire resistance and I cast a fireball to clear the enemies around them. The companion also takes a little damage. The companion then complains at me like I was attacking them maliciously. It's not like other games where they may just snark, "Watch where you're shooting!"
The problem with D:OS (and D&D and any other RPG I've played) is that a lot more work goes into the combat than the other parts of the game. When they showed the alpha gameplay at PAX, it was 100% combat. No one ever bought D:OS to play rock paper scissors, but this was still pretty fun for a persuasion mechanic in an RPG. D:OS is a combat simulator strung together by a story. (
Fallout 4 was the worst-case example of this.)
D:OS is fun, but let's not pretend that "kill everything" is true freedom. This is certainly not what freedom means in my daily life.
I really would love if Larian considered how they would design the game if they completely removed combat as a mechanic. How could they design the game to be equally complex and exciting? How would the player achieve their goals without stabbing everything that gets in their way?
