for, it's a couple things (that is so me)
1. the lack of (good) longer rap-verse in current k-pop, there is not a lot of them
2. there is no school concept that is more-dark or even edgy, it's all bright and colorful, which while, I'm glad that it exist, the fact that it's just that, kills me.
3. the lack of variety in vocal style in k-pop and even just korean music in general, is actually hurting me because . . . there is no excitement for vocal-heavy songs, if they don't have unique way of singing of vocals, now, this is always a thing in k-pop but I am more critical of now since I have been listening to k-pop for 7-8 years now and started to listen way genres of all music as well.