I just read this post from Jim Hines about the killing of major characters, and it reminded me of a pet peeve. Basically, it seems that everyone I read on this topic believes that any death of a major character needs to have a good reason within the context of the story. I really disagree with this.
How many deaths have you seen in real life that fit neatly into the 'story' being played out by the friends and family of the deceased? The truth is that death tends to come rather randomly, except in the case of those dying of natural old age.
I have a character that is traveling with two others through a land where most people are fleeing an invasion. While passing through a nearly deserted, looted village, a couple of refugee teens throw rocks at the men from behind a house, striking the horse of one character in the eye, causing it to buck crazily. The character is thrown, and unfortunately his neck strikes a fence post. He is paralyzed from the neck down, and after some fuss convinces his comrades to put him out of his misery.
Does this death fit neatly into a storyline? Not really. I liked it, because it contributed to the realism of the story. This is what life does - it throws randomness into things. People may not like it, but I see it as if I am writing the history of what happened, rather than trying to tailor every last point to specifically fit the story.