No, it's got nothing to do with Korean authors. It's simply yaoi 101.
Perhaps you are right, i must say i only saw this (as well as the dicks bigger that a forearm trope) in korean manhwas (and it happens often) but perhaps it's not limited to them yep
(it's just like american manga have a different art style and tend to represent bodies in a much more realistic manner, it's like the art differentiates itself depending on where it comes from, we are witnessing culture creation at its finest this is beautiful)
Yaoi manga is in a class of its own. Lol. Exaggeration of the male anatomy; dick, balls, abs, shoulders, back etc. is normal, and in fact expected by the mostly female fujoshi fans. So it has nothing to do with real life Korean men but the authors fulfilling the fantasy of their readers. Lol
FINALLY
I WILL BE ABLE TO SLEEP AT NIGHTS NOW.
(this might be excessive, but i'm glad for them, though i don't see how things could go well when the prince finds out our captain is missing)
also it's crazy how he's been locked up for months without being able to get out of bed and has been druged and all, yet his muscles are still in tip top shape! :D
that's korean men for you! they're just built different (in their author's head only)