Simply because we acknowledge that a child is incapable of making a responsible decision in such important matters does not make them any less equal. Mentally retarded adults are equal, however they REQUIRE guidance for the rest of their life. Why? Because they have the mind capacity of a child.

Do you suggest that God wants us to put children out on their own, to act as adults and to fend for themselves?

It is quite simple. The father plays a "god-like" role to a child. Hebrews 12:4-11 illustrates how God and earthly fathers are alike. A small child cannot comprehend God, therefore it looks to what it knows, it's parents. How they represent God will be judged by God.