Thank you! Yeah I agree before Netflix it was also mainly OCN which broadcasted this kind of dramas and from what I can find they only had 2 dramas before 2010. So probably indeed there just aren't that many before mid-2010s.
I've watched Ghost, I hear your voice and Liar game (the Korean remake).
Ghost is good, the second half drags a bit, but overal it's solid drama. I really liked Mad Cow who was my first favorite crazy detective. He's a bit annoying in the beginning, but he grows on you.
I hear your voice is great too and the same for Liar game (but at least in case of the Korean remake it's possible that you can't stand the main character, it's how her character is supposed to be, but yeah it can be annoying to some).