People like Dan Brown who broker lies about Jesus do so to achieve their own nefarious ends. Giving credence to the falsities which underlie the Da Vinci Code only serves to promote error and confusion about Christ and his teachings.
Furthrmore, if it were true that Jesus married Mary Magdalene (which it manifestly is not), it could diminish his "Messiahship" and his glory as revealed to us in the historical Christ. For one, a non-celibate Christ undermines the image of Christ as the bridgegroom of the Church, which was discussed by Christ (Mark 2:19) and by John the Baptist (John 3:29).
Do you think the church, as the bride, should be barren? Spiritually speaking of course. As I think about it, you present a valid reason for Jesus to have been married and a father, for it establishes a natural happening upon which the spiritual allegory can rest.