Probably because of the magnitude and scope of WWII, the First World War was never given much more than a historical afterthought. Yet it is one of the pivotal points in all of human history, when centuries old monarchies and empires, some being the derivative spawn of imperial Rome itself, were wiped off the map or toppled to a minute fraction of their power.
The result was to leave the door wide open to the secularist and often ideologically driven nation-state we have today, not to mention the world empire ambitions of globalism. We are still feeling the effects of that war and will continue to do so for the indeterminate future.