Sexism of Asian drama fans?

It seems Asian drama fans and especially kdrama fans are ok with noona romance, and there are lot of noona romance dramas, but very few dramas where the man is much older. I think it's ridiculous. I love this sexist attitude because in real life, and the western world, older men x young women are common and shown in dramas way more often and people don't care. Jdramas portray lot of relationships where the man is older and people are ok or at least neutral about it. Chinese dramas did lot of older man romances too despite some people hating. 

It seems to be a kdrama problem in general. Is this a cultural thing in Korea or what? 

 Lou:

I dont truly think it is a Korean or Chinese thing. It is probably more a generational thing. Most watchers are very very young, and you see that well in the shift of korean dramaland. Productions are moving away from serious topics and more to the typical high school/college themes. And kids who are in their teens and early 20ties are finding it harder to imagine relationships with people that are the same age as their eg. teachers.

It gets easier the older they get. So let's see :) maybe things change again. 

Okay, but how does that explain why  Kdrama fans hate on the older man, but not the older woman In the relationship?