WARNING: Major SPOILERS below for Star Wars: The Last Jedi. Do not read ahead until you have seen the film.
Star Wars: The Last Jedi is both a revolution for the franchise and an evolution for its characters. These changes manifest themselves in ways big and small. For the character of Kylo Ren, his evolution is one that has come with a physical transformation. When we first saw the leader of the (at this point, imaginary) Knights of Ren, we saw a villain wielding a badass cross-guarded lightsaber with a menacing voice and a Vader-esque mask. The mask became a part of the idea of Kylo Ren before we even knew much about him. But we eventually saw the man behind the mask and learned about who he was. Now, in The Last Jedi, Kylo Ren has destroyed the mask for good and marked the end of a transformation for his character. As director Rian Johnson explained, losing the mask was not an easy decision, but it was one he felt he needed to make. Here's why:
That was the big design choice with Kylo: losing the mask. It was a little terrifying because, by the time we were making the movie, the first film had come out and every kid was wearing Kylo Ren masks on Halloween. It was the symbol of the movie on packaging. And I love the helmet. But the whole premise of this film is that you're getting inside this guy a bit more. More than that, Rey is seeing there's more to him than she thought. And Adam Driver is one of my favorite actors working today. The notion of getting the mask off of him so we don't have to deal with it and can look into his eyes seemed really important.
Watching Star Wars: The Last Jedi, there really is no way the film could have worked if Adam Driver had worn the mask the majority of the time. As Rian Johnson says in The Art of Star Wars: The Last Jedi (via ScreenRant), looking into the actor's eyes was really important. The emotional connection between Rey and Kylo is the emotional core of the film and for it to ring true, we had to see his face. Eyes are the window into the soul and Kylo Ren's was a soul in conflict. For Rey it is far easier to hate a man in a mask, a symbol of evil, than a real, living person with sadness in his eyes. The film dives more into who Kylo Ren is, the events that have shaped him and why he ultimately makes the choices he does. This all comes through in Adam Driver's performance and it wouldn't have been nearly as impactful or believable -- or perhaps even possible -- had the character remained masked.
In The Force Awakens, Kylo Ren fancied himself a new Vader, like the grandfather who he idolized and worshipped despite never meeting. Using a mask that echoed the aesthetics of Darth Vader's was Kylo's way of trying to live up to that lofty dark side ideal. But ultimately he was only playing the part, a fact that Snoke criticizes him for in _Star Wars: The Last Jed_i, leading to Kylo destroying the mask. The prequel trilogy chronicled Anakin Skywalker's transformation from Jedi Knight and hero of the Republic to Darth Vader, the strong right hand of the Emperor and boogeyman to the Rebellion. This transformation manifested itself physically, until Anakin became unrecognizable. His eyes turned that Sith yellow as his soul was corrupted from the inside out, until eventually, thanks to Obi-Wan knowing the value of the high ground, Anakin became someone else entirely. The armor and mask represented the completion of Anakin Skywalker's transformation into Darth Vader.
Kylo Ren had a parallel journey but in the opposite direction. For Adam Driver's character, killing Snoke and shedding the mask represents the completion of his transformation from Ben Solo into Supreme Leader Kylo Ren. This film has a theme of moving on from the past and for Kylo Ren that means letting go of childish desires and becoming his own man. What is fascinating to me as I begin the long wait for Episode IX, is how much more compelling a character Kylo Ren has become. Although killing your father can seem like a move you don't come back from, there was still conflict in Kylo in Star Wars: The Last Jedi. Near the end, he seems more resolved, especially after there is no longer a mask to hide the conflict in the man beneath it. By removing that mask, Rian Johnson may have given us the most complex Star Wars villain yet.