Since You are all-powerful, why do You need us to praise You or prophesy or tell others about You? Couldn’t you just do anything You needed to to get the word out to people? Angels? Words written in the sky? Why do You need us?
The Psalmist asked this question, too.
“When I consider Your heavens, the work of Your fingers, the moon and the stars, which You have ordained, what is man that You are mindful of him, and the son of man that You visit him? “ Psalm 8:3&4
We can’t always know the “why” of things when it pertains to understanding the mind of God. All of us have many, many “why”’s which may never be answered in our lifetimes.
But here’s what we can know: God has made it obvious that He does care about man. And He does choose to use men in His plan for the earth. He lets us praise Him. He lets us prophesy. He lets us pray. And He chooses to use all those things to spread His truth. He could use any number of other spectacular displays of His glory, or methods of communication, and sometimes He does, but mostly, He chooses to use men.
Why? Just put that on your list of things to ask Him someday when you are kneeling at His throne.