I gonna drop the obvious from my side:
Open would be negatively impacted if PvP would be disabled.
No, I do not think a pacifist mode would benefit the game.
Also, comparing Elite to Fallout is comparing apples and bananas or whatnot.
If we want to look at a comparison, we can compare Elite and Eve, which have way more similarities than Elite an Fallout have.
First, Eve is a space genre kinda of game, Fallout is not. Secondly, the communities of Elite and Fallout are very different whereas Elite has parts of the Eve community within as quite a few players enjoy both, Elite and Eve at the same time.
So I would say that looking at what was "shocking" for Fallout has little analogy to what might be "shocking" to Elite.
Now with that in mind, let's imagine what would happen to the better comparison example if it would disable PvP.
It would die. Instantly. Eve without PvP is not Eve. The community in Eve greatly engages in PvP and without it, many would drop it.
Elite might not be as hardcore and dedicated as Eve but it certainly is closer related to Eve than it is to Fallout.
Thus, no, I don't think there should be a pacifist option for open. People who dislike PvP but still want to meet players can join Mobius. People who generally dislike PvP can play in Solo. Open is for everyone, PvPers included.
Currently, the status quo with the modes is mostly tolerated. Shifting it to either side will cause unhappyness within at least one group of the Elite community. For the game, it's probably for the best to not touch game modes.
For me personally, I would appreciate a shift towards Eve's design of multiplayer.