When I did my student teaching just south of Berlin Germany in what was formerly under communist rule, the host family I lived with was adamant that I see the bad sides of Germany, as well as, the good sides. And they especially wanted their children to see it so they could also understand what had come before. As much I as I did not want to visit a concentration camp, I am thankful for that experience.
Yes, the past is relevant to the future and we should continue to teach this to the next generation. Good, bad and the unimaginable. Children can learn from all the good choices, as well as, the bad choices. Teaching relevance of the past to the future should be a prime focus in schools.