In concept: yes we should absolutely do them. It should be the remit of currently-existing society to seek justice, and on the stage of nation states one state committing injustice against the world cannot be resolved except by ad hoc systems like these enforced by the winners of an armed conflict. Also it's important to get all of the middle management guys in an act of genocide to make it clear to future generations that "I was just following orders" is no excuse.

In practice: it has mostly been a method by which the powerful countries consolidate their control over the rest of the world and launder their reputation. They say to us: "look at this long list of African and Middle Eastern warlords and all of the atrocities they committed with child soldiers and suicide bombers" while never prosecuting a single westerner for the atrocities they committed with spreadsheets and aerial drones. Milošević gets a trial for his role in the Yugoslav Wars, but nobody was held responsible for the sanctions against Iraq in the 90s which killed an estimated 500,000 children.

Perhaps someday we'll see a successor/evolution to the UN that actually gives some kind of proportional power to all member countries, instead of being either a rubber stamp or a powerless observer to what the Security Council was going to do anyway, and we'll be able to establish meaningful international law. Until then, we're stuck with the version that was created by and for the bourgeois dictatorship.