I won't entirely bother to pontificate on citizenship and historical knowledge, but that's something to keep in mind as well.
If you're a democratic person, you will perhaps believe that an average person should be exposed to both our inner demons as well as angels. If you're more of an aristocratic person, you may want to hide the masses from undesired content,, but expose those most worthy with the knowledge of the otherwise undesired content. Regardless, someone will have to know it, to be better prepared. Depriving the elites of this knowledge won't serve them well as they lead their societal inferiors. Depriving a democratic people of unsightly knowledge doesn't lead to a better informed aand wiser leadership when they are expected to help take the mantle.