Yes it's stupid to complain about violence in the story but it's even more stupid to believe there's noting wrong with how 90% of the yaoi is ending up with the rapist and victim.
Before you get me wrong, I don't find it stupid for people to be upset at the toxic relationships. I find it stupid when people complain about aspects of the story or dynamics of the characters when it's already been explained. The "man" is an Oni and a mean one at that, so it doesn't take many braincells to determine this is NOT going to be a nice love story.
Personally, I love a violent action packed story, but I can definitely do without the rape and it's completely possible for Korean authors to write good stories without it.
I get being annoyed at the rape/smut (even though its been like this for years and they don't have any plans to stop writing it), but the setting is in the underworld with demons and spirits...so you sound stupid complaining about the violence and lack of humanity.