It does reduce the stakes if characters don't really die. I feel sorry for Supernatural's writers at this point. They had to introduce a Reaper whose entire purpose appeared to be to restore the danger associated with mortality. "No, this time I'll make sure you're dead-dead, not just Winchester-dead." There's possibly a tolerable exception: when that's important to the plot. eg: Frank Herbert's [The Godmakers] includes a 'resurrection' requirement before a character can be considered a candidate for godhood. The POV character dies and is restored; and in this case it's not a trope, but rather, a plot inflection point. And sometimes it's nice to resurrect a character just to kill him again. One of the only good things about Star Trek Generations was that we got to see Kirk die twice. I was assuming the first time killed his body, and the second time was necessary to take out his ego.