I also would very much like to see negotiations amount statistics in Global ranking window. To be more specific, negotiations statistics should be only about "won negotiations" ,not "all negotiations" or "lost negotiations". Same as battles number in Global rankings reflect only won battles.
Negotiations compose another playing style of this game - peaceful playing style, which is exploited by many players. And also, negotiations are one of choices, to go through Continent map, Guild expeditions and Guild battleground. So seeing this statistics would improve information about any player and would allow to get a clearer picture, what playing style the player prefers.
It would also benefit when recruiting new members into guilds.
Don't know how Inno engineered negotiations in their programming code, but from my programming experience, this feature should not be hard to implement.