I think the base idea of parley isn't a bad one. Negotiate through diplomacy is an interesting option that could definately be fun and change the pace of just stabbing anything that gets in your way, however fun stabby stabby is. In the overall story it fits i think because while your in opposition with the beast tribes.
Your also part of a group that is seeking the bring them into the fold of the resistance against the Empire
It sucks because the mini game itself is blah. But Diplomacy controlled by an AI is a crap-shoot of Bleh in most any game. Theres just few if any ways to really make a back and forth negotiation either feel real, be non-repetitive or feel like anything but pushing numbers around. theres no real way to bluff when you have an advantage and not have it feel like just more RNG chance.
I'm sure if it was more written out like a story/ conversation it would be better but its will still be kinda the same thing.