Here's another way to look at it. Maybe it was not such a unilateral decision by God. Perhaps He counseled with us, and outlined for us some of the conditions that we would live under during our time on Earth. We were spirit children, and we had never known pain or neglect or wanted for anything. We lived surrounded by God's love. But we needed to obtain physical bodies, because we had progressed as far as we could in spirit form. There were things to learn that we never could have learned without ever facing adversity. Perhaps we were full of confidence that, yes, we knew it would be hard, but it would only be like a small moment in our eternal experience, and soon we would be back home. So maybe we said something like "go ahead and give me all you've got. I can take it. I want to know what it is really like. I will learn, and I know that I can always call on You for help when I need it." And God could have said, "Are you sure, my child? I do know that you can do this, but I will hurt for you when I know that you are hurting." And we came to an agreement about which challenges and ordeals we felt we would really learn from. Sometimes the families that we had wanted to be part of were not living up to the challenges of mortal life in the way that we hoped, but we loved them when we knew them in heaven, and we hoped that even though we would be weak and small at first, that we would be able to help them somehow and to show them the love that they had forgotten. And maybe God asked us, "Are you sure that you still want to go to those parents? They have forgotten so much, and it will be a hard life for you." And we said yes, because of the love that we had for them.

Maybe God tried to talk us into easier choices, and we chose the lives that we have because we knew that we had much to learn, and we wanted to be with the ones that we loved. Or maybe we were given the option between challenges of one kind or another, and the set that we chose were what we felt that we could learn the most from or deal with best or help somebody the most or make the most difference in the world.

I am sure that the decisions made were not random, and that we knew and agreed to what we would face, even if we couldn't entirely comprehend what it would feel like when we were in the middle of it. But we believed that it would be worth it, whatever it was, and knew that it would be for a relatively brief moment in our eternal existance.