Where I think people get tripped up, is that they somehow expect a movie to explain everything about the characters, even if it's not vital to the story at hand. Yes, a team film first isn't likely to explain all their origins, background, supporting characters, etc., but it's likely to be a good INTRODUCTION, show their powers, their personality, and what they stand for.
It's one possible good introduction. It isn't the best one and has just a higher risk to those franchises within WB itself their solo movies wouldn't.
Solo movies would be much better in establishing the solo heroes, especially complex characters like Wonder Woman then a paper thin characterisation in a JL film where they'll contantly be in jeopardy of being overshadowed by Superman and Batman.
And, really, The Avengers isn't a great example, because there's reason to believe that Iron Man, Thor, and Captain America could support solo franchises in the first place.
And? WW, GL, Green Arrow, Aquaman, Flash and numerous other DCU properties could all sustain a solo franchises.
Marvel apparently doesn't believe that they need to do an Ant-Man movie to understand him in The Avengers.
Marvel is making an Antman film IIRC.
Not that he's a good example for solo franchises. He's more like Martian Manhunter, though J'onn has had better luck as a solo hero.
Antman's a C-lister whose primarily suporting cast in Avengers. Personally I think he has the potential to be more but that isnt going to happen so it's besides the point.
The B-listers like WW, GL and Flash have more then enough potential to make it as solo movies.
You probably could do an Avengers movie with it beginning with them finding Captain America frozen in a block of ice before a solo film. Captain America's origin really isn't that interesting, he gets a shot of super soldier serum, but what he stands for is interesting.
There's more to Cap then being soldier who was injected with super-steroids.
Being from WW II and being revived in the modern era would be a good enough concept to make a solo fim about to introduce him to the audience.
His origin has always been interesting to me. Not many heroes have such a fascinating origin to explore.
There are pros and cons with each approach.
True.
The Avengers approach is asking a much bigger commitment of time from actors and is probably more expensive as they're going for already established stars to launch the solo movies, and have a proportional paycheck. How they're going to pay everyone and keep the budget within reason still isn't something Marvel has answered.
While JL has many B-list franchises which never reached their potential in solo projects in media since WB has practically ignore them and will bury them at the slightest hint of failure.
WB should have been making the solo movies and other projects higher priorities decades ago.
They aren't covering their flanks in animation or live action tv shows like Marvel has been doing, either. They have gotten better but their successes dont encourage DC to move forward with them as a continuous franchise. They ignore themafter the show ends which allow them to go back to obscurity which in turn negates the franchises being established with the public in the first place. That is not the way to keep make the lesser franchises solid. WB still has not found a way to give the lesser franchises access to multi-media simultaneous and multi-generational sychronicity only Batman and Superman have enjoyed. That's a severe disadvantage for any "new" solo franchise from DC.