I would assume since death was so prevalent then, opposed to long life today it was considered more of a religious and accepted thing. I would assume that in antiquity death was a widespread concern and it motivated religions because the span of life in those days was shorter than it is in our time. I would also dispute the accuracy of this point. The span of life is longer nowadays in prosperous societies only, not throughout the world. Furthermore, the concern with death and the desire for an afterlife do not seem to me to have diminished.
Initiation is a very important role for the transition from youth to adulthood.
Thus Sophocles offers in Philoctetes a heroic model that men of his own time may admire. The citizens of fifth-century Athens may mold their lives after that of the hero they worship. The update of Homeric heroes places them in a situation that continues a purpose of the previous epics. Sophocles' plot places the Homeric heroes in new situations but does not alter the characters they had in the epic tradition.