Christ is risen! He is risen indeed!
Why was the stone over Jesus' tomb rolled away? He was already gone. A mere stone cannot keep the resurrected Lord from escaping the throws of death. No, He didn't need the stone rolled away. But we did. It was for our benefit. That bolder was dislodged and the grave open so we could look in and see that Jesus was gone.
The angel told the first lookers; "If you're looking for death, you won't find it here. Jesus, who was crucified is not here, He is risen! When we look into a dead situation we can trust God that He has the power to bring resurrection out of it. I believe that He wants us to look at death and see life. He wants us to understand that "all things" really do "work together for good for those who love Him".
Really, the whole cross event(death, burial, resurrection of Christ) was for our benefit. God does not need us. He is perfect! He needs nothing. From creation to redemption God did it all for us. He isn't missing anything. But, since He is love, He has done it all to love us and to show us that love.
Somewhere in eons past--in a time before time--God made a decision that His nature--His character would be love. He is a giving God. That's who He is. He gives because that is what He does. He doesn't need to give, He just gives. He doesn't need our praise and thanksgiving, it just comes naturally to Him when we realize that the stone was rolled away for our benefit.