Why did God create a universe that allows for human suffering? Perhaps because understanding and then overcoming evil is necessary to achieve the highest good.
Right. So instead of just creating humans who are capable of achieving the "highest good" on their own, which an omnipotent god would easily be able to do, he decided instead to condemn millions of innocent children to a life of torment and suffering.
Your God is a maniac, and you are morally bankrupt if you try to justify children suffering in the name of "the greater good".