Jesus wanted His followers to see prayer as normal and as necessary and foundational as oxygen. And in teaching about prayer - rather than teaching a “how to pray” seminar - Jesus taught more about what God was like in character because He recognized that our vision of God will directly impact how we relate with God.
But if God really is all powerful, all knowing and unchanging and also knows what we need before we ask anyway - why pray? Does it influence God? What is the purpose in prayer?
The purpose in prayer is what Jesus was always interested in ... communion with God.