Why do I need to pray for God's will to be done when God's will will be done no matter what?
God is trying to teach us to love. Preeminently, prayer is an act of love. Every time we pray, we are exercising our will to love someone or to love God. Prayer elevates us and elevates our love because it is a call to love. That in itself is a beautiful thing. God wants us to become part of loving our fellow persons. In order to do that, we have to pray. His will is that we learn to pray so that we see the connection between prayer and loving each other.
May God bless you.