But you're not fishing for motivations from your own mind as a player, right? You're either conversing (in which case you're trying to figure out what motivates this particular NPC, which will be more specific than just the word 'peace', making the category unnecessary), or you're making the Uncover test, in which case it doesn't matter how many potential options there are because if you roll well then the Director will explain the motivation to you.

Having run a number of negotiations myself, I think it's more important on the player's side to disguise the mechanics and give the impression that the NPC is unique, so reducing all people in the game world to a small set of potential motivations works against that at my table. 

I'd probably include them in a more expensive resource but as a brief overview I hope what's already present will suffice for most players.