Show Why Joker is More Than Just 'a Batman Villain'
With a half-century of experience and stories under his belt, reducing The Joker to 'a Batman villain' is as inaccurate as describing Darth Vader as 'the bad guy in Star Wars.' He's a villain of primal force, an elemental monster as much as a flesh-and-blood human... which is where movie adaptations have seriously fallen short.
There's no real mystery as to why: Joker may be more than just a Batman villain, but he still is the best known Batman villain. That means when a Batman movie, TV show, video game, animated feature, or even animated series needs a big bad, Joker is usually the one to get the call. Unfortunately, that makes him the villain to beat; the villain to Batman's hero; the character existing to serve another character's story. And that's the main reason why no other medium has managed to create the same breadth of stories, styles, philosophies, and mythology of The Joker as comic books and graphic novels.
Alan Moore made The Joker the star of The Killing Joke, and it remains one of DC's best selling books. Brian Azzarello did the same with Joker, and was instantly placed alongside Moore for exploring what makes this well-known, but completely unknown villain tick. To give Joker the spotlight in a movie - a spotlight he doesn't have to truly share with Batman - is the obvious next step. And if you're looking to tell a story that movie audiences have never seen before, humanizing, dramatizing, and scrutinizing the reasons behind The Joker's evil ways is almost certainly the most intriguing.
Placing Joker opposite Batman without any explanation of how he got there may be interesting on the surface (people fear the unknown), but what if a writer or director wants people to do more than just fear The Joker? What if audiences can be made to not sympathize or agree with The Joker... but understand him? Does that honestly make subsequent or parallel versions of the character less interesting to watch or discuss? It was the step needed to begin a new chapter for The Joker in DC Comics, and it's well past due for the movies.
Stop The Restrictive "Shared Universe" Assumptions For Good
Now we move from the fictional 'red flags' thrown up by the mention of a Joker origin film to the structural/DCEU/shared universe ones. The explanation is straightforward enough: this new Joker would not conflict with Jared Leto's version in a Harley Quinn vs The Joker movie, since it would be set years before, and played by a different (younger) actor. Not only that, but it won't be framed as a 'prequel' to the DCEU Joker, instead allowing it to tell its own story without having its end chapter already written and expanded itself. Yet the idea of having not one, but two Jokers in separate films, in separate points of their life, from separate creators... is already a contradiction online commenters see as a guaranteed disaster.
In all honesty, it's disheartening to see how quickly Marvel's "shared universe" approach has transformed from a single Thanos-focused story to the only way the average moviegoer can make sense of adapting characters from the same licensed universe. Not only that, but any suggestion that a character adaptation will deviate from this strict formula must now be met with confusion, pessimism, and belief that the studio has absolutely no idea what it's doing (Spider-Man fans can't see how Venom could share the screen with Peter Parker and NOT also include Iron Man, Captain America, Thor...).
We've previously explained how the DCEU avoided Marvel's issues from the start, and acknowledging that The Joker is flexible enough to support two different adaptations is a similar no-brainer (especially when so many doubting this decision also derided Leto's Suicide Squad rendition). On one hand, the DCEU Joker is played by an Oscar winning actor - on the other, creators are telling their own story of how The Joker came to be. Not the DCEU's Joker-- The Joker, the one every Batman fan knows like the back of their hand.
Call it an Elseworlds, call it an origin story, call it a spiritual prequel - whatever keeps the skeptics from drowning the project in negativity before it enters production. But at the heart of the doubts appears to be the rationale that only one version of a DC character should get to exist on film at one time. And as much as different versions, targeting different audiences, with different goals and different actors may risk 'confusing' the average moviegoer, robbing them of the choice seems the far crueler solution.