Mmmm.... is your question aiming at a moral reading of the play, perhaps? I have to disagree with the basis of your question. I don't think this play is about lust so much as about love, and the stupid things we do when we are in love. However, to backtrack, key to understanding the play is understanding the context.
Twelfth Night was a festival in Elizabethan times that was even more important than Christmas itself. It celebrated Epiphany, the time when traditionally we believe the three kings arrived and gave their gifts to Jesus. However, in Elizabethan times it was a festival that celebrated excess and chaos. Heavy drinking, cross dressing and a topsy-turvy social order were celebrated. This was before the end of the Christmas period and the beginning of January and a new year. Traditionally we take our decorations down after Epiphany on 6th of January. So, understanding this festival more allows us to draw many parallels between the action of the play and its title. Sir Toby Belch and his cronies are celebrating to excess this festival. When he asks in Act II scene 3:
But shall we make the welkin dance indeed? Shall we rouse the night owl in a catch that will draw three souls out of one weaver? Shall we do that?
This explains the completely chaotic nature of the play - capturing this Twelfth Night spirit, characters are inflicted by the "disease" of love and suddenly are completely infatuated by people they have just met, often below their social standing, for example, Olivia and Caesario. Thus I am sorry but I have to challenge the basis of this question.