My seat-of-the-pants take (which I could qualify linguistically, but I think it's fine to posit these concepts colloquially in this context) on this: Most successful human languages provide a similar complexity space within which to express oneself richly.

You need to be able to communicate mood, underrun expectations, frame or defy relationships ... in English, much of this is done by choice of words (especially adjectives and verbs) and word arrangement. In Korean, instead, while there's a giant repertoire of nouns, sentiment and relationships are more often injected via choice of grammar form and word choice is rather more straight-forward.

For example, Westerners make much of Korean's various speech levels ("politeness") which need to be used correctly depending on age or standing of addressor and addressee, and mostly (but not solely) take the shape of different verb endings. But of course English has a complex register system as well - but it's done via word choice and arrangement instead. It's the difference between "I'm sorry, I'm not able to help" and "F*ck off". In Korean, you can conceivably scale this difference by leaving off a word ending aimed at the wrong person combined with body language.

It's this difference - human interaction and the nature of eloquence remain the same in their essence, but the tools of expression have different mechanics - that's fascinating.

(Also, greetings from #rust!)