It seems a good idea, but then I remember the history of World War I: the French and the German populations were very happy and willing to go to war (especially the French). A quick war that will settle it, they thought. And then they ended up in one of the worst meatgrinders of history.

Even if they had a referendum system such as the one proposed, I don't think that would make it a better decision. And given how people don't assume the consequences of their decisions, they would just find excuses later on - "we were manipulated, they lied to us" - but the damage will still be done.