Yes, I agree with your post entirely
I still think it would be better off as an official thing, however, due to quality and creation of all the necessary support for better mods to enrich the system.
Being something like a toggle, as I suggested, you could simply not allow it on your multiplayer server (the equivalent of what you said about not joining a server that has the “pvp” mod) and so there wouldn’t be any unpleasant surprises nor people griefing others that don’t want to
Right now the only way to allow it through mods doesn’t really give much control nor the chances to actually make a diplomacy mod, nor distinguishes factions (from what I understood) so it would still need some sort of official support to make it more customizable even if they don’t really add it officially themselves
Been playing a lot more and with other people and will soon have a new round of feedback :3