Just how suffering in the gym makes us physically healthier.... Suffering in the world helps us grow roots and be stronger of soul. It gives us depth to our human experience. It keeps us connected to all other living creatures and lets us know we are alive (except for your Tsunami example).
The Atheists argument is... the world does not appear as though it has been created by a loving God so therefore no God.
I want to know what would the world would look like if there was a loving God in charge? What qualities should we look for?