Death is a constant reminder of the end- mortality- so we want to reassure ourselves that we are still part of the living and build hope.
The symbols and meanings attached to death are not fixed because individuals have different experiences, circumstances, and thinking that change the metaphor and context.
Since we cannot control death, we use metaphors to help our reasoning of it. Our personal culture, ideas, myths, our fears and hopes, all influence our understanding of death.
So, we may continue to use death as a metaphor for the future since neither can be controlled. And a lot of great poetry has been written because of it. From inspirational to the macabre, death is a constant theme in our lives.