Most korean Webtoon is romance genre, and although there are other webtoons, romance brings in the most money so it is constantly promoted. Fantasy or scifi stories just aren't very popular.
Usually they will have a full team working, so the art quality is typically very good. One sad thing I noticed was that Koreans have very high standards for art, so even if the story is very good, if the art is mediocre, it will get lower ratings. One webtoon I saw was called 달의 요람. Overall rating is 3.07. If you actually check it out, the art honestly isn't that bad, and there are even comments that defend the artist. But ratings are still very low.
Artstyle is also a big point in webtoon. I don't know if non-koreans can do this, but most Koreans can tell the difference between American style, Japanese style, etc. If your webtoon has similar traits to Japanese style, you might get a few comments about it. And western webtoon has more diverse art styles, so when I saw Lore Olympus on Naver webtoon, I checked the comments and many were saying how it felt awkward that the characters weren't normal skin color.
It's just a difference in culture. Many forget that Korea is a monoethnic country and complain that there isn't enough diversity. Some of my friends have never seen a person of color before.
One thing about korean webtoon that I like more is the horror. Koreans write very good horror.
Sorry I wrote so much, this has been something I was thinking about for a long time 