Cause we're all perverts lol
It's just for visuals ig, some manhwas don't have it
coz lots of bottoms irl are feminine, heck even some tops irl are also feminine. The masculine looking ones (if gay), tends to be more bi for real, that's why that "straight dude" appeal is such a big thing in several gay communities-- it's a treat since lots of 'em tend to be really feminine themselves, so much so that they've developed some level of hatred and discrimination for that look/lifestyle which is so ironic and stupid if I do say so myself.
Relatively, it's also creative license on the author's part if that's their preference + it panders to the market's demands (we don't want the creator to be a starving artist now, do we?)
just wondering
why are bottoms so femenine to the point that they look like womens