George R.R. Martin received so much kudos for killing Ned Stark that other authors may do the same. It's been said that killing the main character made the story so much more real and compelling and so it becomes very tempting to do the same thing. That execution was something of a novelty, but Ned's downfall came from his own faults, as admirable as those faults may be. Subsequent writers may miss this point and simply set up a protagonist and then kill him or her for the shock value.