Boruto introduced a lot of new characters for the next generation of ninjas. It also presented some new designs for older established characters from Naruto. Many of these new designs were met with praise. Ino, Shikamaru and Sakura received upgraded looks that fans felt honored their characters. However, this same level of appreciation was not given to Naruto Uzumaki's new look. In fact, many believed that Naruto got dealt a bad hand with his adult design.
It's natural to expect that as Naruto got older, he would look more rugged or powerful. This is the typical trend for most shonen protagonists -- they get cooler with age and time. But Naruto almost follows the opposite of that rule. As Hokage, Naruto has lost a lot of the wild and fierce appearance of his younger years. He also looks less battle-ready and sports a much more relaxed demeanor. Even though these design choices aren't "cool," they perfectly fit the role that Naruto has in the story now.
Naruto Shouldn't be a Clone of His Father
When fans offer suggestions on how Naruto's adult design could have been improved, they often point toward Minato Namikaze. They want Naruto to look more like his father, which is understandable. Minato has one of the best designs in the series -- he has a strong silhouette and an appearance that radiates power. When people look at Minato, they see someone who could be an intimidating leader if he wanted to be. Why shouldn't Naruto strive to emulate that same look?
Although Naruto is the son of Minato and carries some of his attributes, he is his own person. Naruto has gone through his journey almost independent of his father. He's overcome challenges and defeated enemies that Minato could have only dreamed of. Turning Naruto into a copy of his father would only lessen the accomplishments that he's achieved.
By creating more differences between Minato and his son, Naruto becomes more of his own character. Where Minato had a leaner face and longer hair, Naruto has a fuller face and shorter hair. Part of Naruto's story is about him surpassing his father and following his individual path. Minato and Naruto are two different Hokages of two different eras. They shouldn't be compared as much as they are. Naruto has found his own way of doing things and a look that fits his personality.
Naruto is a Hokage of Peace
For years, the ninja world has been plagued with wars and conflicts between nations. This strife has required leaders to always be vigilant and create a certain persona. The threat of attacks or being conquered by another village was always present, so previous Hokages had to make themselves appear powerful and intimidating. The first Hokage, Hashirama Senju, was one of the most feared ninjas in the world. He used this fear to protect his village, but behind the title of Hokage, Hashirama was a very kind and goofy man.
Now that the ninja world has settled into an era of peace, the intimidation tactics of the past are no longer needed. There is no threat that the Leaf Village will be invaded or thrown into war. Because of this, Naruto is free to be more friendly with the other leaders. His objective isn't to strong-arm the Kages into obedience, but rather to foster comradery and peace. His new design communicates that fantastically. As an adult, Naruto looks patient, understanding and compassionate.
Naruto's new look also has an air of professionalism to it. The Kazekage, Gaara, has also adopted this aesthetic. The spikey and wild hair of their younger days might have been cooler, but this doesn't quite fit the appearance of someone who leads a nation. Gaara and Naruto look like people with important jobs that they take seriously. Being Kages in this new era of peace requires them to go for a more toned-down look. They must look and behave more like men of the people.
Naruto is a Father Before Anything Else
It's a major plot point of Boruto that Naruto thinks of everyone in the village as an extension of his family. Every man, woman and child in the village is someone he has a personal responsibility to protect and care for. Naruto can be seen giving interviews, helping villagers with mundane problems like carrying groceries, and securing the defense of the village. For all of these tasks, Naruto needs to be approachable. The villagers need to feel like they can come and talk to him about anything, and his friendly and open design gives that impression.
Naruto's adult design screams dad. His round face and short hair make him look more like an average person. Naruto doesn't need to display the insane amount of power that's held inside of him. This would only make the villagers hesitant to communicate with him. Naruto's goals are for every villager to view him as a "lame" old man, the same way Boruto did. As an adult, Naruto's design might not be as "badass" as many people wanted, but it shows a level of maturity that he's gained with age. He doesn't feel the need to impress anyone like he did when he was a child. Naruto only wants to make his people feel comfortable and lead them to a better future.