A world without death would be torture.
Overpopulation, starvation and other interconnectings will rule the land.
We would grow bored with life and suicidally depressed. Suicide would, of course, fail, making us even more depressed.
We would never be able to comprehend the idea of grief.
We would grow old and useless without any relief.
The gates of heaven would be rusted shut, and hell would run out of people to burn.
Eternal life, at least in this universe, would be damaging.