Why did Jesus come as a child?

If God's plan was to save humanity from itself through Christ why did the Messiah come as a baby?  Now there have been books written on this by much smarter folks then me, but in keeping with my Christmas theme for the season "The birth was just the beginning", I wanted to look at this question.  God could have done a number of things in this redemptive process.  Christ could have just shown up with an army of angels and wiped out all the sinners, problem here is that would have been all the people.  Christ could have come down from heaven, climbed on the cross, proclaimed he was payment for all sin, but that lacks full commitment.  For Christ to be the full payment for the world's sin he had to be fully committed.  This means he had to be fully man and fully God and that starts with his birth as a child.  Through the Gospel's we see a full life.  We see a perfect life.  We see temptation over come, we see anger, we see weeping at the death of a friend.  We see love for children, love for the widows, love for the poor.  As John says in closing his Gospel there were so many things we don't know about because he could not write them all down.   We see the lessons we needed to learn lived out in the perfect human form.  We can believe these lessons because they were taught by Christ, fully man.  Most importantly we see that every spike nailed in his hands and feet, every lash of the whip, and every drop of blood was real.  Was spilled with all the pain and suffering that we too would have felt.  This was no easy plan for salvation, and this redemption was not cheap.  This was the death of a man, a man who was fully God.  For that to happen Christ had to come as a child.  The author of Hebrew's says it best in Hebrews 2:16-18.  16 For surely it is not angels that he helps, but he helps the offspring of Abraham. 17 Therefore he had to be made like his brothers in every respect, so that he might become a merciful and faithful high priest in the service of God, to make propitiation for the sins of the people. 18 For because he himself has suffered when tempted, he is able to help those who are being tempted.  I for one am greatful that God chose this way.  When I pray I pray to the one that has experienced it all.  I pray to the one walked among us.