"If you’re old enough to remember when it was released, the revelation that Vader was Luke’s father was shocking! You gotta remember that at that point, nobody knew who or what Vader really was. Was he a machine? An alien? Something else??? And Luke was told that Vader murdered his father.
So in that one iconic line, we learned that not only was Vader Luke’s father, but there was actually a human being underneath all that metal and wires. It was powerful."