I don't think the comparison is well chosen WCH...
Besides this, look at Eru's gift to the two races. While the Elves are indeed immortal and are forced to wait what may seem like an eternity for the world to end, Men are given the Gift of Death and for this it is said they are envied by both Firstborn and Ainur.
So death is indeed an uncertainty, something humans must all bravely face, but in the end they are rewarded.
Btw, I always thought that when dealing with this topic Tolkien also tried to make the reader feel that death isn't that bad after all and to put it into a new light... kind of a rebirth away from the troubles of the world. But, this is not the topic at hand.
