The reason I love this work is the reason I love most of Nakarmua Asumiko's dark works over her fluff works (not to say I don't like them, but her dark works are just more satisfying for me as a reader), she does not laugh off a serious situation. In BL it's common to gloss over or make funny an issue that should be taken with more severity. For instance in J no Subete, J is a cross dresser and perhaps Trans. He isn't a cross-dresser because he is envious of woman, he isn't a cross-dresser because he needs to be comedic relief in the series, it's because this is the form in which he can express himself best and may relate to the issue of being trans here (it is mentions in the manga but in a lot more caustic tone by the people around J). As for the incestuous relationship between J and his father, she is perhaps addressing the carefree tone of incest in BL (like Papa to Kiss in the Dark). It is not always something to gloss over; it is sometimes a severe crime on a child who does not realize the seriousness of the situation. I say that the child dose not acknowledge because in J no Subete, we as the reader are supposed to know that the situation is far from loving, but J in the first volume dose not view it in such light. In volume 2 J seems to acknowledge the situation in a different light, how ever.
I do believe she is taking these approaches with purpose because of other BL points she's made in her dark works, like in Double Mint. Double Mint has the kind of BL trope of one partner continually chasing the other regardless of how badly they're treated. But instead of laughing off the situation at the end where the two have finally gotten a hold of being together and one of the two still exhibit spurts of aggression, we have an example where the manga itself acknowledges the dysfunctional of the relationship and although the two characters do end up together, as the audience, we are aware of the dissatisfaction and abuse. We are aware of the serious repercussions of this relationship.
With all of this said, manga is something that is, for some, a way to enjoy a suspension of disbelief that is kinder then reality. Confronting these issues with such a serious tone maybe off putting and conflict with what some likes in manga and are seeking. I enjoy the confrontation and the respect that Nakamura Asumiko brings to these tropes and to the genre in general, but to each there own.
-A