I studied koine Greek with my dad. Today, I study Aristotle alongside half-a-dozen English translations (the latest, Adam Beresford's Ethics, is hilarious, "like Han Solo and Chewbacca, Achilles and Patrocles" in the notes; his Aristotle uses "Perhaps...but that's a bit off-topic").
None of the English translations is as convincing as knowing the original vocabulary. Many phrases and idioms are still obscure or debated. Why should the student not want to look behind the curtain?
Finally, there is something bracing about knowing the ancient grammar. Greek has features long-vanished from English.
You would separate students into those who never need to bother looking a bit into "foundational to western literature" and those handful who are on a PhD track. Eventually, nobody would grow up to be recruited into the latter.
I find ancient Greek not so helpful when it comes to etymologies. Some are helpful, but many are obscure or misleading. Climax comes from the word for a ladder apparently, and electron comes from the word for amber. There are stories behind both but they won't get you far. Any word beginning with psych- tends to relate to the mind, but the Greek means "soul".