A character being boring or under developed is the fault of the writers who often get overly distracted by their crazy plots, their shiny toys, and their own obsession with other characters/ideas. And if the writers feel that the only way they can remove their now boring and defunct character from the narrative is to kill him (in spite of what kind of thematic, moral, or ethical message it sends) then you have to question, at the very least, their artistic integrity. It’s lazy for people who’s jobs are literally to tell stories and figure out a way to develop their characters and ideas in organic ways. There’s nothing wrong with killing a good person in TV. It happens all the time and in other shows can be handled with grace and thoughtfulness that serves their other characters and their narrative.
There is,however, a problem with killing a good (morally upright) character in TV simply because *writers* don’t know what to do with them or find them uninteresting. And the fact is, in recent history on this show, the characters who are getting killed off are those who are 1) parents 2) definitively morally upright (meaning they have not committed any egregious sins such as the big bad one of murder) and 3) were met with hostility from parts of the fandom and moreover their deaths are never given any kind of weight or meaning. They just simply exit stage left and the other characters go back to focusing on plot.