I think the CB is dying because the game itself provides no viable CBs. By now, everyone knows that spying isn't really worth the effort. Same goes with poaching, or aiding alliances at war, or whatever. Much easier to forgo these insignificant behaviors in exchange for peace.
Furthermore, the game is so old, the 'societal' standards so well-established that anyone with half a brain following the general "how to avoid war" CN rulebook has nothing to worry about.
When some incident pops up, those in the disadvantageous position will follow the rulebook. Everyone's an optimist, they'll always think that waiting things out will tip the scales in their favor later on. By the time that happens, the newly disadvantaged side will follow the same rulebook, and the same hopes.
On the off-chance someone does something stupid and insufficient steps are taken, alliances will either ignore/cancel/not activate treaties to prevent escalation.
I think the community needs to redefine what an acceptable CB is. I do agree that generally, noCB "we don't like you's" are pretty bland, too easy. Why not make certain actions alliances take that is pretty vital to their growth/well-being, and make them war-worthy?
So, "stealing our tech deals" or "cancelling our trade circle" (lol yev) or "not voting for our senator".... some of these sound ridiculous, but that is the point! Alliances have to think at some point that war, even a losing war, is preferable to caving into ridiculous demands.
Granted, the mechanics of the game is the biggest constraint on coming up with stuff that's actually worth going to war over (there is very little scarcity, a scarcity of scarcity ) but I would not rest my hopes on any changes being made in that realm.