Before flagging my post, please read it all. I'm not trolling, and maybe you won't agree with what i wrote, but please try to discuss it in a civil way. Dividing ourselves in almost political parties won't benefit anyone except people that want the game to remain broken. I know the post isn't exactly short, but there's much stuff to talk about and i tried to compress it as much as i could while trying to make it readable.
First, what "Diplomacy rework"? The type of rework i'm refering to is the 3K/Troy type where you have an accurate representation of the values used to calculate if a deal is going to succeed or not + other additions like settlement trading and easier alliance system. Which, since is one of the most asked rework for WH3, you might be familiar with it.
The biggest reason why people want it is that it will make the game easier: if you know what the AI likes you can manipulate diplomacy, and if you can manupulate diplomacy then you can also manipulate the AI and make the game easier. Things like that can be the difference between starting a war against the N°1 strength ranking faction, or maybe "smaller" but more powerful deals like a treade agreement while playing TK.
Well, if you didn't see it above, here's the problem: manipulate the AI. Honestly, the AI in this game is not smart, and while i think it will get better in the next game it still won't be at the same level of the player, and this mean that "any idiot" will be able to cheese the game to insane levels because, while yes you can now spam stacks of overpowered heroes and T5 units and basically win every 1v1 battle (which on top of that you can force 1v1s via lightning strike), you can technically lose your wars if you are not careful enough (which is hard, but not impossible).
With the OP diplomacy that has been proposed you won't ever lose. Hell, you won't even need to doomstack: if you can pick your allies and enemies you can just go for T1 crap and spam AR. Won't even need any money cheese like entrepeneur because you can just force your allies to give you rich land or just give you money all because you spam sacked a single settlement and then have 1k relations with them.
Also, this will break the few challenging race mechanics like the Dwarf's book of grudges that are not tainted by some cheesy crap. I mean, even lorewise, can you see a dwarf knocking on someone's door and asking peacefully to return their land for some ammount of cash? Of course not, a dwarf will probably break that door and slaughter everyone inside. And maybe after half the people living there lack their head then they will start doing "diplomacy".
WHAT TO DO
Well, i know the actual diplomacy we have is not perfect, but imo if the alternative is that kind of crap is better to keep it as it is. If a rework should be done and done properly however it should reflect better the chaotic and hostile enviroment of the Warhammer World, which mean you shouldn't be able to see KaK ally with Clan Mors, or even just get a lot of relation with a faction by whatever mean. Leaders of the WW know better than to trust the first guy that happens to share the same enemy with them. I don't say good relations shouldn't be possible, but that things like military alliances shouldn't be considered a tool to get a reward, they should BE the reward.