I think the reason why they don’t talk about this topic is because of how conservative South Korea is. Any korean idol/celebrity that goes out of their way to talk about important topics (such as feminism, LGBTQ+, mental health...) usually get a lot of hate and backlash because they are not doing what “they are suppose to be doing” which is sing, dance and please their fans.
Also, the korean music industry is way different than the western industry, the singers are extremely controlled by their companies. Matter of fact, blackpink said in an interview in 2017 (I believe) that they were not allowed to drive, have social media accounts, drink, do drugs, go to clubs, get tattoes, get plastic surgeries and/or get into relationships (because those are things that have made a lot of korean idols loose their reputation or even their career) . Then they explained that if they wanted to do those things they had to ask for permission and they would probably let them do those things but at first it’s a no no.
Pd.: sorry if I’ve made some mistakes but english is not my first language, but I hope my message helped you to understand a little bit more why they have to be so “cryptic” with what they say and do.