Because everything is presented as a parody. "They did it because they were crazy" or "they did it because they hated women". Truth is, for a lot of things, there is at least some reasonable justification that makes more sense, which is not to say that it's necessarily or automatically completely correct. We now know a lot more than they did, although in many ways we are much less wise.

Also, the witch-hunts took place in the early modern period. Don't blame the poor medievals for those.