I think diplomacy was something lacking in AOK and AOE3, it has always been too solid, you went in a game and most of the time the person you went in the game allied to, you stayed allied with throughout the whole thing and you didnt really forge alliances mid-game. It isnt too big of an issue, but if the devs have something up their sleeve concerning this, that would be great. Realistically, diplomacy is a huge issues in conflicts and economical disputes, but in AOE3 and AOK it didnt really have a big impact.