"But surely God is omnipotent?
None of the bad stuff has to happen!" - MintyMoocow
In a dynamic universe, it's inevitable that bad things are going to happen, and chains of consequences occur that lead to cycles of destruction and creation... crime, earthquakes, infectious diseases, wars, asteroids, whatever etc.
The point of God's omnipotence is that he's infinitely merciful, rather than necessarily interceding on every little last thing that would lead to a catastrophic or traumatising string of consequences. Imagine if God did intercede on everything that might lead to a bad outcome...
"Nope." <breaks chain of connection between event and outcome>
"Nope." <breaks chain of connection between event and outcome>
"Nope." <br... etc etc
The universe would quickly seize up into a static, meaningless lump of nothingness, with no joy, no wonder, no awe, no beauty, no love. There would be no consciousness. Just preprogrammed robots, with one mode of operation. You up for being an inert, unthinking robot? If you want freewilled dynamic consciousness for yourself, you have to accept it for others as well, even if it clashes paths with you.
God lets the universe cascade out according to the free will of its agents, but his divine love and mercy imbues the cosmos and travels along the pathways carved out by pain and suffering to heal, for those who choose to accept it. People who complain about the absence of God are like those standing outside a friendly, cosy pub on a dark night, complaining that they're lonely, cold and hungry, but refusing to simply walk through the door and find the warm fire, hot soup and a friendly conversation inside. You're standing in your own way. Walk through, and receive.