So, MC wanted to try topping, was shot down and...

I rlly do see your point (and i think this is recurrent in these manhwas) but i also feel like what the author of this specific one wanted to put across wasn't this but that he couldn't find pleasure in bottoming until he was w someone who actually cared abt making him feel good. I think it was important that the past partners (w the tiny dicks) were also shown to not have much interest in their partner's pleasure and had no technique, making his sex experiences unsatisfying. I think the mc was looking for guys w massive dicks bc of this, and tbh i think if he wanted to try topping he would have by now

No, I get that it wasn't intentional here. It's a bit funny through with the previous author's work... (I will leave it vague for spoiler reasons, but you probably could guess).

This time author went even in a weirder way about addressing it through. Cause 1st boyfriend we saw (not in chronological order) wasn't depicted as selfish or uncaring to him. Maybe lacking in technique or literally in equipment. But the only truly uncaring one was his first love that saw the seed of doubt, with his own issues about bottoming. And than we got this weird scene of him not getting pleasure even with the bigger caliber of a sex-toy. And essentially training himself into getting enjoyment out of being a size queen lol

Sure other options wouldn't be addressed by now, I agree. I also think that if it was solely about finding a partner that would focus on his pleasure (there would be less attention to how Jungseok does what he wants while pretending to ask first) and not the size kink. There more hilarious route would be to pair him up with a partner with a small dick (which probably would be drawn as average irl anyway) who would know how to use it. Can you imagine wildly popular guy with a nickname Flaming cock having a small one?