If the aftermath of WW1 were the re-arrangement of the European power balance with Germany purposely spared, then we still live with a very tangible consequence of WW1. The existence of Yugoslavia, the Czech Republic and Hungary among others is a result more or less of the post-war measures taken to dismantle the Habsburg Empire; the preservation of Germany was just as much a conscious decision by the Allied victors. Could you imagine how different our political landscape (not to mention 20th century world history) would be had the Allies decided to liquidate the German Reich in 1918?
On the inter-war rise of the dictators: viewed from the macro-political perspective it is a story of the failure of collective security, with nations joining the League of Nations but withdrawing as soon as they found a better way to stay secure of expand; either by pursuing unilateral, aggressive action or cozying up to the ‘rogue’ nations which would later form the Axis. One could say that the League and collective security were in fact a political experiment gone wrong; something intended to replace the old shifting alliances and power blocs, but could not in the end for a number of reasons (lack of enforcement mechanism was one for starters).
Consider the key loopholes in the Allies’ attempts to uphold Versailles and collective security: a) the lack of a League army, US support, and effective enforcement mechanism (all inter-related) crippled the League; these weaknesses showed up in a big way during the debacles of Manchukuo, Abyssinia, Anschluss, Rhineland, Sudetenland, re-armament, etc., in the sense that the Allies could only threaten but never bite, making unilateral action relatively easy. Also b) the fact that the lynchpin and ‘victim’ were both paradoxically the same entity, namely Germany. It was up to Germany to behave and comply with Allied and League demands, yet there was little reason for it to do so and as Hitler’s actions after 1933 show, little way to enforce it. The post-war status quo therefore fell apart quite quickly once Hitler realised that unilateral action was a viable option in the face of Allied reluctance to fight.
It would seem that a balance of power was achieved via the old power blocs because they could bite. On one hand was the key involvement of the old power blocs in the escalation of WW1 through a spiral of war effect; on the other hand a League which was bound by its own principles (couldn’t shift or manoeuvre politically) and relied on its members to fight its battles (which none would) lacked the clout, versatility and muscle to deter aggression in the way the old pre-WW1 power blocs could.
What seemed from the outset like a stabilising force in Europe – a multinational and ‘non-partisan’ power bloc devoted to the proper reconstruction of a de-fanged Germany for the good of a stabilised Europe – turned out in fact to be a power vacuum. The League was too bound by its charters (as were its members) to engage in pre-emptive aggression (though economic and political reasons, war-weariness, situational misreading and simple fecklessness all played a role). The only other potential check on the Reich was the USSR, but for most of the 1930s it was simply too alienated and introverted to do much. In any case it played by its own rules not the League’s, and had no qualms with collaborating with the Nazis when expedient (witness the Ribbentrop-Molotov pact).
This left an aggressive Germany, unfortunately on whom the whole fabric rested, free to dismantle the status quo with relative impunity.