Also I think it's because of vertical format?? Similar with how TikTok works Idk but whenever I read webtoon especially those with explicit scenes with not much dialogue i can't help but to continuesly scroll up but when I'm reading a manga my fingers have a time to stop and observe what are in the panels before flipping the page, artstyle is also a factor
Now that you mentioned the exaggeration of movements and expression in mangas I think that's also a factor why their works looks a live, I feel like this also one of the reasons why watching cartoons are so entertaining and fun even though we now that their movements can broke their bones in real life
I've actually found quite a few colored ones that do well, but for this one in particular, the art is rather stiff and needs work to make characters feel more human? They move their limbs rather restrictivly and as an artist, I'm assuming it's just something that needs more practice with anatomy. The movements are too safe, which makes characters feel, well, less flexible? Less lively and to a fault.
Kinda unrelated but while colored webtoon's sex scenes are indeed hot, it's just feels so dry...? . Don't know how to explain, but it's just feels so dead and stiff, like it's just hot but you can't imagine the movement or can't feel the passion properly unlike Japanese manga which obviously have more panels and drawing and dialogs. Ofc I'm not only talking about this webtoon, that's why I'm still kinda salty that Korean webtoon gay porn is more popular than Japanese manga gay porn here. I guess people just love to see colored dicks.