“And [Yaakov] took his two wives and his two maidservants and his eleven children” (B’reishis 32:23). Although Binyamin was not born yet, Yaakov already had twelve children, as Leah also had a daughter, Deena. Why does the Torah only refer to eleven children if there were twelve? Rashi, based on the Midrash (B’reishis Rabbah 76:9), tells us that Yaakov had hidden Deena in a “box,” so that Eisav wouldn’t take her against her will. For doing this, thereby preventing the possibility of Deena positively influencing Eisav, Yaakov was punished, and Deena was taken by Shechem instead. Was Yaakov really expected to risk his daughter’s well-being on the remote chance that his wicked brother could be rehabilitated by her?
Once we place the conversation between Yaakov and Eisav in this context, Deena’s potential role becomes more prominent. When describing what could have been, the Midrash (Shir HaShirim Zuta 1:15, http://tinyurl.com/lz57a6y) says that Eisav would have married Leah (and Zilpah) and Yaakov would have married Rachel (and Bilhah); kings would have come from Eisav (as they are responsible for making sure that society runs properly) and kohanim would have come from Yaakov (as they are responsible for the nation’s spiritual growth). After Yaakov took over both roles, though, Yaakov had to marry Leah too (and Zilpah), and the entire nation came from him. Where would that leave Eisav, had he accepted Yaakov’s offer, since Yaakov and Leah were already married? Yaakov may have agreed to work for Rachel for seven years in order to give Eisav a chance to marry Leah (see page 2 of http://www.aishdas.org/ta/5768/vayeitzei.pdf), but once Yaakov had to marry Leah, if Eisev ever reconsidered, who would be his spouse? Deena was Leah’s daughter, and had the potential to take her place. By keeping Deena hidden from Eisav, this possibility was removed, making Yaakov’s offer for Eisav to reclaim his original role more difficult to accept. Therefore, Yaakov was punished for hiding Eisav’s potential mate, the one who could have “returned him to doing/being good,” from him.