WWI ended with the Treaty of Versailles which officially ended the state of war between Germany and the Allied Powers. This Treaty was signed on June 28th, 1919. One of the most important provisions of the Treaty was the War Guilt Clause which Germany accepted the responsibility for the War. As a result, Germany was disarmed, made territorial concessions and pay reparations.
I think people see modern objects and appliances and they just get ideas on how they can improve those things. But they need to have an open mind to have the ability to get new ideas.