I am indeed proposing there's a crucial difference in perspective here. I doubt time is the only factor, but it's true that the errors of those who lived in the distant past seem more childlike than those made by folks living in the present. We're still attached to our errors and our myopia to appreciate their gross arbitrariness. In addition to time, an elevated philosophical perspective or perhaps a genuine religious one provides some of the distance needed to understand what's really going on. Humility is also required, the willingness to sacrifice some self-esteem, to humble ourselves before horrific possibilities.