Sri Chinmoy: Creation is for satisfaction. When we create we get joy. When we compose a song we get joy; when we write a poem we get joy. God felt the necessity of satisfaction for Himself and for all of us. Without satisfaction we cannot last even for a second.
God was quite perfect when He was the silent Brahman, when He was in the trancebound state. But He felt the necessity for creation because He felt that remaining alone could not satisfy Him. He was a tree without a branch. Then He said, "No, I want to have quite a few branches." Then He said, "No, branches are not enough. I want to have leaves." Then He created millions of leaves. So we are all His creation.