MarkJason:
Or like in Kdrama where it's OK if the older person is a woman, they call it noona and have so many stories with older women x young men, even boys it's kinda creepy, but when it's an older man it's wrong.
I can't really speak about Kdrama as I don't really watch it but I don't think it's the production fault. It is more about the sentiment of drama watchers in general, and maybe the newer generation would prefer the older women X younger man trope, then it's understandable the Kdramas would try to fulfill that demand.
To be fair, some years ago there's also an opposite opinion about why public would be okay with older man dating younger woman and not okay for the other way around. I guess it must have been evolved from that era, that we now see more of the latter. And I think older Kdramas don't have problems portraying older man X younger woman pairing, at least in those that I have watched like in Jang Hyuk dramas for example lol.