A quote at the end struck me as level-headed. A man said he knew better than to really wish he had lived in the 13th century because he had had tuberculosis as a child, and in the Middle Ages that disease probably would have killed him.
When I was six, my adenoids started growing into my ear passages. If they hadn't been removed, I would be deaf now. And since I'm severely nearsighted, I'd be almost blind without corrective lenses. On the other hand, my (shall we say) ample figure would be more in style—assuming I had sufficient money to maintain it. Only the well-to-do could afford to be plump back then.
That got me thinking about fantasy literature, or at least what is sometimes called sword and sorcery or epic fantasy, as opposed to urban fantasy or magic realism. In some ways it's a past that never existed, and in others, it's the past as we would like it to have been. Would Gandalf have allowed the Black Plague to happen? Of course not! Any wizard worth his or her salt should be able to deal with minor problems like deadly bacilli.
Think what history would have been like if Richard III had had Merlin on his staff at the Battle of Bosworth Field. Or if Joan or Arc had had more substantive and useful visions--say a genie in a bottle who could sweep the English from French shores.
But maybe it wouldn't have made that much difference. Maybe our biggest problems come not from external forces but from within. Merlin couldn't really help King Arthur, after all. Even in fantasy, magic has its limitations, just as people do.