And less susceptible of being abused by the player.
What I suggest is that hostile actions by the player against a Faction should follow a “3 strikes policy”, so you get 2 warnings and then it’s war.
Right now you can balance wrongdoing against a faction by doing wrong to the other factions, abusing the system to fast forward diplo relations with all the factions and to gain massive amounts of resources.
IMO, the worst thing of the current diplo system operating on the basis of abstract rules that make no logical sense is that it prejudices the new players (who don’t expect - or I didn’t, at least - that the fastest road to being loved by all the factions is to be as much of a di** to them as possible in equal measure), or those players who don’t bother doing the meta maths.
What a reasonable person expects is that attacking a Faction, especially repeatedly, will lead to worsening relations and, pretty soon, to war.
So what I suggest is that attacking a faction once will reduce the diplo rating and provoke a response in the vein that “we hope this was a misunderstanding.” The second attack will cause a bigger penalty to diplo relations, and the response will be “this is your last warning”. A third attack will mean war.
What this means is that now as the player you have some interesting choices to make: you have 2 “free” attacks against each faction, will you use them to improve diplo relations with other Factions, raid for resources, or steal aircraft? You can’t do all without going to war.
IMO, this also corresponds much better to player expectations.