Rabbi Frand points out that every time Moshe Rabbeinu warned Par'o and his court about an upcoming plague, he would immediately leave. When someone must convince someone to act, it is best to allow that person to save face and appear to have made the decision on his own. Otherwise, he is likely to refuse to "give in" to pressure, even if it is the best thing for him to do. We see that also in the reaction to the plagues in which Par'o "strengthened his heart" (which in Hebrew is the symbol for the will). He could not allow himself to be "threatened" by a group of unruly slaves and diminish his "honor".
Rabbi Frand also points out the necessity for a man to have a wife. He needs someone to look on a situation from outside but who will be considered "part of him" so that he will listen to the advice.