Walt only killed bad people, but had he not done what he did, many good people would have lived. Walt's actions made him responsible for Hank, Jesse's girlfriend (can't remember her name), the other chemist that Jessie killed (his name slips my mind too...long day), all of the people on the airplane, not to mention that Jesse's life would have never gone that far either. Jane wasn't a "bad person" either. I HATE that he ended up getting what he wanted in the end. It makes sense for the show, and they did an amazing job making things work out, but I felt that at the end, they justified what he did, and that to me made the whole show miss the mark I thought they were trying to hit all along.