Let's get something straight. WB is not Marvel Studios. WB does not have the luxury of only making superhero-related projects. That's just not how it is.
What Marvel is doing is pretty cool, but ultimately, not exactly what JLA requires. JLA isn't some pseudo-government black ops organization brought together by an outside organization. It's a bunch of heroes realizing they need to come together to combat greater threats. That concept doesn't require, even at it's most complex level, a series of realizations from movie to movie. It simply requires showing that they came together, and their recognition of why, via a, drumroll please...greater threat.
And let's face it, the quality of Marvel's approach has yet to be determined. Recent Marvel films have been, with the exception of IRON MAN, pretty average to subpar. There's no guarantee Zak Penn's AVENGERS will be any good, either. IRON MAN was fun, THE INCREDIBLE HULK was decent, at best. A hint that there's a larger universe makes the codas of those movies slightly more interesting, but not the movies themselves.
The reason not to show the origins of the DC heros is simple. Their respective origins are largely irrelevant to the basic concept of the JLA. Even in the comics, whenever "origin stuff" comes into play, it often feels forced, and more like a shorthand way to explain character's motivations than actually delving into them. I.E, want to explore Bruce Wayne's conflict? Have him and Superman flashback to their origins every five issues, instead of exploring their similarities and differences.
If some creator comes up with a fantastic JUSTICE LEAGUE project, one that makes sense, that is well done, that WB is willing to make and bankroll, and one that talented, appropriate actors are available for and enthusiastic about, I'm not going to "No! Wait seven to ten years in the hopes that maybe Christian Bale, whoever plays Green Lantern, whoever plays Wonder Woman, whoever plays The Flash, and whoever might play Aquaman, J'onn J'onnz, etc, etc, etc would want to make that movie as well as one to three of their own!"
That's. Just. Silly.
It's all about the project. It should be about the project, first and foremost, not how it ties into the other heroes movies. I get it. In a perfect world, we'd get two or three DC hero films a year, and a Justice League movie to follow.
This isn't a perfect world. Copout or not, there are logistics involved that make such a thing very, very difficult, and frankly, a little unrealistic, although who knows, maybe that's what will happen.
As far as continuity issues...you all want JLA to avoid contradicting or treading on what is set down in the other movies?
Here's a simple idea that people, for some baffling reason, seem to be unable to pick up on:
Simply don't address the other movies and their events and supporting characters at all.
Don't talk about Superman's son or him leaving the Earth, the details of the Batpod, or the fall of Harvey Dent (although, if you did, these things could STILL exist in a JLA universe, and simply not DRIVE it).
Now, of course it's not that simple, but at the same time, it's not that difficult either. Give me an example of something you don't want to see in JLA or something you don't want treaded over, and I'll show you what I mean.
Why do we need to know that Bruce Wayne's parents died taking him home from The Gray Ghost when we saw in Batman Begins they were going home from Faust?
Why, pray tell, would any JLA writer bother to make this alteration? Bruce Wayne's parents were killed, period. Why would a JLA movie writer, knowing that some people would be sensitive to the details, ever address the details of this stuff?
It'd be counter productive to undo all of that backstory, and while there's no need to have Bruce go referencing things like Harvey Dent or Rachel, I do think that it'd be wise to pay attention to continuity while writing the film.
Pay attention to continuity in what sense?
I think that JLA's story should be self contained in that you don't need to have seen all of the other movies to understand or appreciate it, however I don't think that that should stop them from building on the movies that come before it, and tying things together in a way that you can view it all as a single universe through the movie.
Examples, please, if you don't mind.
Likewise, your enjoyment of the solo films should not be limited based on whether or not you've seen JLA, and if you'd rather not acknowledge it and simply go on viewing the Nolan Batman films as their own universe, nothing will be stopping you. If they really want the JLA movie to feel like a truly epic team up of classic heroes though, I'd rather they go all the way. I know it's becoming a bit cliched to make a Marvel comparison, but if Marvel doesn't need separate, "elseworlds" versions of Iron Man, Hulk, Thor, and Captain America for the Avengers, then why can't DC do something similar with its own heroes?
I agree. A JLA film should simply be written so that it doesn't delve too deeply into the details of any hero's past or future adventures or fates to prevent confusion or continuity issues for people who care about such things. Sort of like every issue of JLA ever written, with a few hiccups.
In my mind, with only a few movies/characters to worry about, and not YEARS and YEARS of stories like the comics, all this requires is a little common sense. I.E, you don't show things like major characters dying that are planned or wished to have future adventures that take place after the timeframe JLA is set in. This really shouldn't be a confusing concept.
Only fans call the concept of a JLA movie that doesn't directly reference the other DC movies "Elseworlds". It's JLA. It doesn't NEED to reference those other specific details that aren't broad themes inherent to each character. As I've said, Batman is Batman, Superman is Superman, etc.
I mean, this is literally the SMALLEST issue fans should have concerns over.