As Pesach is a time to instill true emunah into our children, the entire Haggadah is a textbook on how educate children. The format is question and answer and every step along the way we do things to try to coax the children to ask by themselves. We bring many props like Matza and Marror and we try to relive the story, attempting to take the children back to the excitement of leaving Mitzrayim.
That being the case, asks Rav Eliyahu Dessler (Michtav MeiEliyahu 4:249),why if there are no children must we still conduct our seder in this pedagogical manner? Why say the Mah Nishtanah and not just delve into the story? Why must accomplished Talmidei Chachomim and even Gedolei HaDor who hold a Seder amongst themselves perform the Seder in this childish manner? Why must we ask ourselves the Mah Nishtanah if we are making a Seder alone?
Rav Dessler answers that Seder night is not simply an intellectual exercise. Seder night is meant to internalize the emunah that we learn from Yetzias Mitzrayim. The lessons must be taken to heart and change the way we lead our lives and navigate he world through the prism of emunah.
True that in our intellect we are all Chachomim, says Rav Dessler, but our hearts are Am Haratzim. Our lives are led by our immature heart. In order to teach our childish heart we must teach it like we teach children asking the questions and showing the answers. In this way we hope that we can finally grow up and lead our lives on the same level that we intellectually know we should.