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!)
[1] https://en.wikipedia.org/wiki/Korean_verbs#Finite_verb_endin...
For example: Korean verb conjugations are massive [1] mainly because conjugations themselves are morphemes (or semi-words, if you don't know what it is) and not mutations or transformations thus the set of conjugations is essentially open. Native Korean speakers can probably easily list hundreds of different conjugations with different meanings.
[1] https://pbs.twimg.com/media/CXakcsoUkAEMPaj.jpg for example.