Why Gray Jedi Don't Make Sense In 'Star Wars' Canon
The struggle between light and dark is a cornerstone of the Star Wars mythos, between Jedi and Sith, Rebels and Imperials, heroes and villains. However, there is also an abundance of characters who walk a more middling path, finding a balance between the two sides. These include smugglers, bounty hunters, soldiers, and scoundrels. One thing that has remained in the realm of Legends is a Force wielder who balances the ways of the Jedi and the dark side. These so-called Gray Jedi are in all likelihood destined to remain excluded from canonical stories.
Since Gray Jedi have yet to be named in canon. What little we know about them and their practices, codes, and actions are all considered Legends. A Grey Jedi is defined as a Force user who uses both light and dark sides of the Force with impunity. The Code of the Gray Jedi dictates that there is no peace without passion and no power without harmony. Their code dictates that they must guard the balance and live only in the Force. This calls to mind the Bendu encountered by Kanan in Star Wars Rebels, who claims to be "the one in the middle" between light and dark. While not a Jedi, the Bendu is an interesting Force wielder who teaches Kanan valuable lessons about the universe. Gray Jedi are similar in that they claim to be in the middle and guard the balance. However, more often than not, the Gray Jedi of Legends use this claim to further their own ends, claiming to be serving the balance or defending the Republic with the aid of both sides of the Force, while in reality they use it to amass power and riches.
While the Jedi High Council leads the Order, with most Knights falling into step, there are plenty of Jedi who choose another path in their service of the Force. Some pursue knowledge on distant, remote planets, studying the flora and fauna of alien ecosystems. Others dedicate themselves to delving deeply into the mysteries of the Force, normally seeking isolation to meditate and fast for extended periods of time. While these Jedi do not participate in day to day life of the Order and decline to be generals during the Clone Wars, they are still true Jedi and servants of the light. Even some Jedi who walk the halls of the Temple are considered by some to fall into the category of Gray Jedi. Jedi Master Qui-Gon Jinn, a maverick within the Order who follows his own code, is considered by many fans, and more than one Legends Jedi, to be a Gray Jedi. Obi-Wan himself tells Jinn that "if [he] were to follow the Jedi Code [he] would be on the Council." Jinn is once offered a spot on the Council but turns it down as he does not want to be tethered to the will of the Jedi leadership. These few are the closest to the traditional interpretation of Gray Jedi that we have seen in canon
Possibly the simplest reason that Gray Jedi will not be making an appearance in canon is that they originate from a fundamentally flawed view of the Force. While there are two sides of the Force and a middle ground to walk between the two, what a Gray Jedi claims to embrace about the dark side is not darkness at all. At the end of the Clone Wars, when the Jedi Order falls, they have become blind by their own arrogance and adherence to strict dogma that is far too cold and removed from life to be good. While the Jedi shirk attachments and expressions of love, they drift further and further away from the light. This is partly to blame for why Sidious is able to lay the groundwork for their destruction right under their noses. What a Gray Jedi calls "darkness," things like passion, emotion, and strength, are not inherently evil. It is the motivations and vision of the Force user that determine their allegiance. While the Gray Jedi might walk a different path from those residing in the Jedi Temple, they are still servants of the light.
Source(s): Wookieepedia