Good question, indeed. And, the question about WWI has been asked about many wars throughout history. Social change/growth (and sometimes negative growth) happens as a result of many things affecting society. Revolutions and wars are sparked because the reasons and need for change exist or existed for quite some time. Progressive and aggressive people and poiliticians have either waited long enough or cannot wait any longer and simply force the issues through violent means. Europe, although under the rule of autocrats, enjoyed a level of personal freedom among the captains of industry that led to massive growth in the average person's wealth, lifestyle, and freedom. Such a large scale expansion of the middle class, tied to higher education as well, would have inevitably resulted in governments far more similar to Britain and the U.S. The so-called class system was based on wealth and when wealth got spread around, the class-system would have been reduced with or without the war, it seems. In spite of the nobility (even today!) pointing their noses in the air, it is money that counts for power. And, the industrial revolution forever changed the rules by which who gets it, and how.