Death is an important part of television. Though shows like Friends prefer to milk their drama from the teat of interpersonal relationships, nothing generates a sense of jeopardy like knowing that a beloved cast member could be dispatched at any time. There's a reason Joss Whedon has picked up such a brutal reputation as a showrunner.
Then again, for every death that adds something to a show - every REDACTED, REDACTED, and REDACTED - there's another that comes across as cheap and exploitative. The ones that follow might not have, in all cases, quite derailed the shows they appeared in, but it's safe to say that none of them were ever quite as good afterwards.