Without DNA replication life is impossible.
Living things must replicate their DNA in order to reproduce.
The information recorded in the DNA must be copied so that it can be passed on to the organisms offspring. Without the copying of the information there will be no offspring.
Also multicellular organisms must replace damaged cells. In order to replace damaged cells the organism must copy the information in the DNA. Without DNA replication the damaged cells could not be replaced and the multicellular organism would die.