For those who wanted more of Jared Leto's Joker, then the announcement that Leto would reprise the role in Justice League's Snyder Cut should be exciting. Regardless if one welcomes his inclusion or not, this decision is confusing. The film has been pitched as the idealized version of the original film, and as far as audiences know, Leto was not a part of that movie.
His initial film deal, which was reported the same year Justice League was released, had him tied to a Suicide Squad sequel as well as the rumored Gotham City Sirens. There were also plans for a Ben Affleck Batman movie, which could've incorporated Joker; however, there was nothing about Leto acting in the original Justice League. Instead, Leto's presence will be added during the additional photography, which begs the question why.
The Snyder Cut Has Too Many Characters
While Justice League was altered in the theatrical cut, there was never any indication that Joker played a role in the film. The Snyder Cut will drastically alter the trajectory of the film and narrative, but there is no clear means through which the Joker will play a role in the story. It is unclear what role he will play in regards to Steppenwolf's mission or Darkseid's presence, and it's unknown if he has anything to do with the Justice League forming.
There were also several other actors who filmed scenes for Justice League, but their roles were reduced or eliminated. Two well-known examples of this are Martian Manhunter and Darkseid. However, while both of them play clear roles in the narrative -- Martian Manhunter turning out to be an established character and Darkseid being the greater evil behind Steppenwolf -- it is unclear what role Joker could play.
The Injustice League Could Expand
The predominant explanation to Joker's inclusion is in connection to Lex Luthor's Injustice League. However, in the theatrical cut, Luthor's "gang" only appeared as a post-credit scene, and it only featured Luthor and Deathstroke. It is also as of yet unconfirmed if Joe Manganiello filmed new scenes for the film.
Due to the gradually expanding nature of the Snyder Cut, it is possible the Injustice League is added to fill out the runtime of the miniseries, offering further obstacles for the Justice League to overcome. At the same time, it is possible that the Joker might appear merely as a cameo. For instance, he could be in a flashback, providing an explanation for the Robin suit seen in Batman v Superman: Dawn of Justice.
Leto's Joker Feels Like Fan Service
Whatever the reason, Joker does not need to be in this movie. There are so many things this film needs to do, like further developing The Flash or Cyborg, who have not received their own films yet. It also needs to serve as both a conclusion and a continuation to the established lore Snyder put into place.
For even a four-hour version of the film, there are only so many plot threads one can put into a narrative before it becomes overburdened. Films like Spider-Man 3, for example, suffered from trying to feature too many major antagonists. While Joker's presence in the Snyder Cut is not a reason for alarm, it is a concerning indication that Snyder might be biting off more than anyone can chew.
Justice League stars Ben Affleck as Batman, Gal Gadot as Wonder Woman, Henry Cavill as Superman, Amy Adams as Lois Lane, Jason Momoa as Aquaman, Ezra Miller as The Flash, Ray Fisher as Cyborg, Jeremy Irons as Alfred Pennyworth, Diane Lane as Martha Kent, Ciarán Hinds as Steppenwolf, Jesse Eisenberg as Lex Luthor and J.K. Simmons as Commissioner Gordon. Zack Snyder's Justice League will premiere exclusively on HBO Max in early to mid-2021.