Is not that "it isnt perfect". It never existed. The Hague was created to persecute backwater third world shithole warlords or at best the enemies of NATO. Not to persecute Bush, Obama or Netanyahu.

You can thank the reduction in warfare killing to the existence of the Soviet Union, which united much of the western imperialist powers (Europe, America and its vessel states like Japan, Australia or South Korea) against the first real menace against capitalism in history. That's pretty much the reason why inter-european warfare stopped after WWII. They function as an imperialist block with the same interests. It has little to do with the supposed existence of "rules" or an imaginary "order".

Personally I put quite a lot in the long term reduction in killing down to tech improving with things like the printing press, the internet and such like.