This raises an intriguing question. If his entire essence is futility and vanity, why then was Eisav created?
The Ohr Hachayim explains that Avraham was born to parents who were not entirely pure, inheriting their imperfections and flawed nature. By working hard to refine the good from the bad he succeeded in isolating the negativity, which was subsequently absorbed by Yishma'el, enabling Yitzchok to be born pure and untainted. However, some residue still remained, and that is why Eisav had to be born. His existence served an important purpose: to pave the way for the eventual emergence of a completely pure and righteous offspring, namely Yaakov, whose children were all righteous.
(אור החיים מט ג ד"ה ואם תאמר)
Another instance where Eisav's negative character came to good use was when, facing the monumental task of receiving his father Yitzchok's blessings, Yaakov had to resort to a cunning deception. As the Torah recounts, prior to entering Yitzchok's chamber, Rivka carefully prepares him by dressing him in "בִּגְדֵי עֵשָׂו הַחֲמֻדֹת" - the coveted clothes of Eisav.
The Chasam Sofer offers an insight into why this was necessary, based on the principle that garments and accessories both reflect and influence the spiritual state of the one using them. The Chasam Sofer bases this on the teaching of the Yerushalmi (מו"ק פ"ג ה"א), where we find an account of one of our Sages who possessed a cane that belonged to Rabbi Meir, וְהִיא הָיְתָה מְלַמְּדָתוֹ דַּעַת - it would teach him knowledge.
Rabbi Meir was famous for his great wisdom, so much so that the Gemara records (עירובין יג ע"ב) that in the generation of Rabbi Meir, there was no one of the sages who was his equal. Remarkably, his cane, so to speak, "absorbed" this quality, and had the power to inspire knowledge. The simple usage of Rabbi Meir's cane could elevate the Sage's understanding and bring him closer to the level of holy wisdom for which Rabbi Meir was renowned.
Means of Deception
The Torah's reference to Eisav's garments as "חֲמֻדֹת" - translated as "coveted"-carries deep significance. It characterizes Eisav's very nature, a desire for things that did not rightfully belong to him. This propensity for coveting extended even to the clothing he wore, suggesting that even his garments were imbued with his negative traits.
Yaakov had worked diligently on his character, refining it to the point where he found himself incapable of uttering a falsehood. As the situation called for deceit to secure his father's blessings, Yaakov had to temporarily embody some of Eisav's characteristics. By donning Eisav's garments, he was essentially aligning himself, albeit momentarily, with the negative traits that Eisav personified, enabling him to effectively mislead Yitzchok.
This method taken by Yaakov is captured in Yitzchok's reaction upon realizing the truth. He told Eisav: "בָּא אָחִיךָ בְּמִרְמָה וַיִּקַּח בִּרְכָתֶךָ" - "Your brother has come with deception and taken your blessing." Notably, Yitzchok did not directly accuse Yaakov of deceiving him. Instead, he said that Yaakov "came with [means of] deception", highlighting that his son had to cloak himself in Eisav's negative traits to carry out the subterfuge.
(חתם סופר ד"ה הלא אצלת)