Death as inevitable ending for Men was, apparently, a by-product of Melkor's influence on them (as Andreth tells Finrod in their debate); it was also the marring of Melkor which precipitated the fading of the elves and therefore their departure. However, there is a sort of a poetic revenge (Notes on motives in the Silmarillion, Myths transformed):
"Melkor's final impotence and despair lay in this: that whereas the Valar (and in their degree Elves and Men) could still love 'Arda Marred', that is Arda with a Melkor-ingredient, and could still heal this or that hurt, or produce from its very marring, from its state as it was, things beautiful and lovely, Melkor could do nothing with Arda, which was not from his own mind and was interwoven with the work and thoughts of others"
Of even greater beauty and potence I find the BoLT version of Ainulindale:
"Through him has pain and misery been made in the clash of overwhelming musics; and with confusion of sound have cruelty, and ravening, and darkness, loathly mire and all putrescence of thought or thing, foul mists and violent flame, cold without mercy, been born, and death without hope. Yet is this through him and not by him; and he shall see, and ye all likewise, and even shall those beings, who must now dwell among his evil and endure through Melko misery and sorrow, terror and wickedness, declare in the end that it redoundeth only to my great glory, and doth but make the theme more worth the hearing, Life more worth the living, and the World so much the more wonderful and marvellous, that of all the deeds of Ilúvatar it shall be called his mightiest and his loveliest".
In a 1944 letter to his son, he describes evil as labouring with vast powers and perpetual success - yet "in vain: preparing always only the soil for unexpected good to sprout in". According to The laws and customs of the eldar, the best attitude to all the griefs and sorrows of the world would not be seeking justice, but healing:
"Healing cometh only by suffering and patience, and maketh no demand, not even for Justice. Justice worketh only within the bonds of things as they are, accepting the marring of Arda, and therefore though Justice is itself good and desireth no further evil, it can but perpetuate the evil that was, and doth not prevent it from the bearing of fruit in sorrow."
My final refference would be to Finrod's explanation of hope: of all His designs the issue must be for His Children's joy
.