Like I said, I find the majority of European art before 1800 or so to be fairly dull, so I can't really answer this question. The prevailing technique improved remarkably post-Renaissance, and that's enjoyable to an extent, but the same themes get repeated over and over and over again.
If you're looking for art with an impact, the iconography of Andrei Rublev (and other icon painters during this period) is still massively influential in the Russian Orthodox Church today. 600+ years of direct use and inspiration! The lack of naturalism is not a deficiency.
Oh. My. God.
Andrei Rublev, 1360-1430? This dude? https://en.wikipedia.org/wiki/Andrei_Rublev#/media/File:Rubl...
Yeah he's good, that's obvious. Klimt cribbed from Rublev I bet. Naturalism was never the topic. But note that Rublev didn't do much work between AD500 and AD1300. Because not born yet. This is precisely why I wrote down dates, and why I am insisting on counterexamples instead of vague generalities.
The problem is not a lack of naturalism, it's obvious mistakes in the way the naturalistic poses are attempted. Many of Rublev's icons have obvious mistakes in the way joints are painted, for example - but not all of them or the exact same thing; it's not a style, it's simply a limitation of his skills. Many later painters who were inspired by him have corrected this mistake, not sought to reproduce it.
Not to mention, Rublev lived at the end of the Medieval period, and well into the Renaissance - the period where painterly skill in Europe was revitalized.