Stars die that others might be born. Seeds die that fruit trees might feed the hungry. Unused sperm and eggs die that newer and fresher ones might produce life the following month. People die that younger, healthier and stronger progeny might reproduce.
Of course ours us is a limitless universe. Eternal youthful life would allow us to populate countless worlds. However, until immortality and fast-as-light star craft become the norm exploration of distant worlds are out of the picture.