Imagine the world is so peaceful. No epidemics, no wars and no natural disasters.
Then at this point when human beings live in peace, they will have a stagnant life styles.
Human beings start to become like pigs! Eat, defecate and wait for death.
What will happen if a disaster strike the Earth? Everyone will just panic and die because they will not know how to react to the coming disaster.

Conclusion: constant disasters that kill is good! For it stimulates human beings' mind
so they will become smarter on how to save their lives.