I was not referring to that at all. You refer to racial preferences when casting their usual romances or action or melodramas. I was referring to the scripts. The fact that in the scripts you don't see anywhere how Koreans view other races (let's call them races for now, although today they try to eliminate this useful word).
I also didn't mean that I'd expect a screenplay to have racism as its main issue. But at least include it, give it some space instead of ignoring it as if it didn't exist.
As for instance "Father is strange" included the huge problems pregnant Korean women face in the workplace, to the point of being fired or encouraged to quit. It's not the drama's main plot but it gets extensive attention for a few episodes, enough to make the viewers think. (A more extensive treatment of the subject, extended to a pregnant unwed mother, is in "I Do I Do").
Remarriage of divorcees with children was clearly one of the themes in "Gentleman's Dignity" and, by the way, it wasn't shown in a progressive way. If you don't mind a mild spoiler click to read the blurred part. It was shown as a real problem that the leading lady was right to think was an obstacle to her marrying her love."I don't feel confident in raising someone else's child" (the "child" was almost an adult). Infuriating! Whereas in "Five Children" the issue was shown in a much more sensitive way. The backwards mentality was mouthed by the traditionalist mother-in-laws, where it was realistic.
Or some school dramas which tackle school bullying not just as a small but normal everyday occurrence but as a real horrible problem which can lead to deaths (only one, "Angry Mom", had it as its main theme).
As I said in my original post, the only time I saw racism as a main subject matter was "A Wonderful Moment" a.k.a. "My Little Hero".
No, I would not like at all to have a person of another ethnicity as a main lead of a K-drama as you suggest**. We watch k-drama to see Korean people act in Korean stories amidst Korean culture in a Korean setting. If I want to see an Italian, French, Spanish, Indian or Black American hero, then I can see European, Bollywood or Hollywood content (which I do). And especially not Whitney, that pathetic person who makes clown faces thinking she's funny. I was asked to segment in that team and I declined with thanks because I couldn't stand her antics. (Plus I like at least the 4 leading characters to be at least passably good-looking since we'll be looking at them most of the time, often in close-up, for 16 hours). If I want to see regular or ugly people I can always talk to my neighbours. It's bad enough that k-dramas focus on the looks of the male leads only while extremely plain girls with elf ears get a pass without even acting skills to make up for it. Actually if the person is a very good actor I stop caring about looks completely.
To go back to foreign actors. The German professor, the handsome black guy (we are not told his nationality) in charge of student security and the Thai student in "Moorim school" were perfectly okay, because they were not main characters, and, most importantly, they were organic to the story about an international school. They were not trying to pass as regular Koreans, their being foreign had a valid reason.
And I get very angry with the pressures on American media where you always have to put the token number of black people, and for every negative black character there should be a positive black character. (Coincidentally this doesn't happen for other minorities like Italians, Latinos, Chinese, nor, for that matter, for white characters - there could be a film full of negative white characters and a negative white main lead and nobody would protest). Like in that recent film, "The Beauty and the Beast", where a small 18th century French village was full of black people in regular jobs with nobody finding it strange. I get it that it's a fairytale, but still it was jarringly ludicrous, especially since we all knew it was done not for artistic purposes, not because it was a quirky vision of the creators, but because of external dictates.
Going the colour-blind way works only in operas and musicals, especially in romantic operas, where realism is banned anyway and where (if you're not sitting on the first 8 rows) everyone is tiny as an ant. In cinema and TV with their close-ups it doesn't work that well. And not in realist operas like Comencini's La Boème with Barbara Hendricks. They went into great lengths to bring the action a century later to justify her presence, but...no! It also doesn't work in things like European fairytales, which are already ingrained in our imaginations with a certain look.
Of course this is my personal preference, everyone is free to disagree.