Within the academic study of history, this issue is usually phrased in terms of how contemporary culture affects the ways in which one has access to or understanding of the past. This can be framed negatively as the problem of "anachronism," or of carrying over presentist assumptions into interpretation of past events. This is something historical scholars try to avoid by carefully studying the cultural assumptions of the past to realize that people have different beliefs, motivations, and goals in different periods and societies. For example, while most people now regard slavery and racism as abhorrent and people who support them as morally questionable, in many cultures slavery was simply taken for granted, and certain races were believed inherently inferior. Someone living in 600 BCE who thought slavery acceptable was not a moral monster by standards of that period, though they would be in the twenty-first century.
Current culture can also give readers a valuable level of perspective about events of the past when they step back from trying to understand the past from the inside and look at it as outsiders. For example, from a modern perspective, one would note that in the beginning of Homer's Iliad, the rape of innocent young girls ("war prizes") isn't something seen as a moral dilemma, but instead as a dilemma regarding whether male military leaders' delicate egos are injured over perceptions of status. Pulling back to consider a contemporary cultural perspective prevents readers from glamorizing the past and helps modern society learn from reading about the past.