It's not adding anything if none of the other movies are going to be connected to it, at all.
How so? The movie will be there, won't it? It'll exist? You'll be able to watch it? It may not be part ofthe DCEU, but it'll be one more DC movie.
I'd think they'll be rightfully confused when they see this movie about the Joker, see it's not Leto, assume he's the new Joker and then when they go to another film set in the DCEU they see it's Leto again.
As
@JD and
@Ovation (and others multiple times over the course of this thread) have said, the audience a) won't care, or b) will care enough to be informed about it. In any way, that's not a good reason why not to. You still owe me a good answer to that question.
Which shows they have no real faith in their own Shared Universe anymore, otherwise they'd use Leto and find a way to fit this in there.
It doesn't show that. It only shows that they're willing to experiment, but don't want these experiments to affect their shared universe. We don't know what will happen in that Joker movie aside from it being an origin movie and set in the 1980s. Maybe Batman or another major character dies in it, or something happens that goes in a direction they don't want the DCEU to take. So, the studio has a movie pitch they really want to go with, but not have it affect their shared universe. Setting it outside the shared universe is the really easy answer to that problem.
And besides, as
@Ovation already pointed out, it's Martin fucking Scorsese we're talking about here.
You don't see the MCU just randomly doing standalone "What If?" movies.
Hey,
@Anwar : Why the hell not?
No, it really seems like a very similar thing. True, the "Star Wars Stories" are set in the same universe as the saga movies, but up until "Rogue One", every live-action SW theatrical release has been a saga movie.
They're probably thinking, "If we're going to fail, why not fail as spectacularly as possible?"
[SARCASM]Yeah, I mean, it's Martin Scorsese and the Joker. When have either ever been connected with a good movie, right?![/SARCASM]