Death goes in and out of fashion. The topic goes dormant for a few years, and then someone calls it forth again: Elisabeth Kübler-Ross with her disciplined “On Death and Dying” in 1969; Susan Sontag with her angry but profound “Illness as Metaphor” in 1978 and the empathetic follow-up “AIDS and Its Metaphors,” in 1988; Derek Humphry, with his suicide handbook “Final Exit” in 1991; Sherwin Nuland w