Autolycus - The Winters Tale

While preparing for tomorrows final exam I read more in depth on the character of Autolycus. I found it fascinating that he was a lovable, but amoral, rogue, however his amoral actions are directly responsible for the happy outcome of the play. If Autolycus had not scared Clown and the Shepard out of their wits with his threats of torture and death, thereby convincing them to flee to Sicilia they could not have turned out with evidence that Perdita was in fact not the Shepard's daughter but King Leontes's lost child. If they had not been there then Polixenes would have most certainly not approved of Florizel's and Perdita's marriage. I think that it is fancinating that this rogue, but not a villian, through his deeds that are most certainly not good created an ending to the play that is happy. My question is why did Shakespeare decide to do this? Why include this character at all? Couldn't have the Shepard and Clown have decided on their own that Polixenes was going to kill them and decide to flee? Why should his ignoble actions result in a very happy and desirable ending?