This is true and fair, yet there is another mistake which I see a lot of: thinking that because people didn't live lives as comfortable as we do, their lot was unremitting misery. Kind of the Monty Python and the Holy Grail view of pre-industrial life.

It's important to have some nuance. Different places had different living standards. The French village life depicted in Peasants into Frenchmen sounds grim; English village life around 1900 was nice enough to generate nostalgic books like Lark Rise to Candleford after the rise of the motor car. The peasants in Brueghel paintings are having a lot of rough, unsophisticated fun.

That doesn't mean we should not be grateful for (say) modern dentistry! Of course we should. But if you paint an entirely black picture of premodern life, you may subtly dehumanize the people who lived it.