Disguise is an element used in many Shakespeare plays for similar reasons. It adds drama to the play and is used to accomplish a particular goal. Shakespeare mostly uses disguise as a form of trickery or falsification.
Autolycus uses disguises to engage in his trickery as these two variables go hand in hand. He disguises himself as a peddler selling goods to gain access to the Shepherds sheep-bearing feast. His disguise was a necessity to keep him from being recognized by Clown noting that he had robbed him. His disguises are also important for him to gain what he wanted (money).
Similarly, Polixenes disguised himself to gain access to the Shepherds residence to inquire into his sons affairs. His disguise was essential to hiding the fact that he is the King.
Perdita also uses a disguise even unknown to herself. She is disguised as a poor girl not knowing that she is actually a Princess. This is an aspect of the plot which only occurs given the sequence of events. This element of disguise is important to the unfolding of the plot.
Additonally,Florizel disguises himself as Doricles to hide his true identity as Prince and to cause Perdita to impute that he is an ordinary person as she presumes she is. This was used to highlight the importance of looking beyond the wealth or outward appearance of an individual; His disguise is used to hide his wealth and to test Perdita’s heart. Florizel wanted her to love him for his internal characteristics and not his riches.
Thus, the importance of disguise is to hide the truth. In Winter’s tale it hid the truth only so that it could be revealed later in the play as an element of drama and surprise.