God does not order pain and suffering upon us, we create it with our many independent, self centered and wicked hearts. He just *allows* us to suffer the consequences sometimes.
We decided to foul things up on the garden by not trusting god, so he has allowed us to suffer the consequences... with one exception, there is freedom from consequence (eternal seperation from God), by turning to him in our joy *and* our suffering. God really has the last word, so to speak, when it comes to evil because one truly saved cannot be lost, no matter the amount of suffering.
I believe the purpose in suffering lies in the way we respond to suffering. God wants us, he wants us to rely on him and only him for our lives. Suffering allows us to see that we do not control all of our circumstances, we are not in control of the world - it is a collective effort. Suffering has a way of bringing us down to a level of need, and God designed us to need him. He wants us to need others and to give to others in need, to reflect how he gives us what we need in life and for us to share the goodness of God and see his goodness in others. Suffering makes one compassionate to others, as God is compassionate to us.
We are designed to be dependent beings not independent of one another and not independent of God, and suffering, although I'm sure it makes God sad and in pain for us, opens a door to him and the miraculous healing he gives so freely if we accept it, trust him completely and look toward his love for guidance and peace.