The fact that we're not getting origin stories for these characters before their big team-up is risky, but exciting. Superhero origin movies can get tedious (just look at The Amazing Spider-Man), and are sometimes unecessary. While it's important to flesh out who a character is before placing them in a cape and cowl, some heroes simply are who they are, fully formed. Aquaman and Wonder Woman, for example, are born with their abilities, in mystical places. The Flash and Cyborg, however, are given their powers by accident, so that will have to be addressed. While many would have liked to see a Flash, Wonder Woman, or Aquaman film before Justice League, it's not completely necessary. Introduce them here, then flesh out their characters as we go along, telling us about who they are, why they fight injustice, and where they come from. If you're still on the fence about the character introductions coming within the team-up, take another look at Bryan Singer's first two X-Men films. They did a great job at introducing us to a host of characters, while finding a delicate balance between the film's stars, supporting characters, heroes, and villains. Zack Snyder could take a similar, albeit much larger, approach.
James is a 24 year old writer and filmmaker living in Portland, OR. He attended college for graphic design and writes for various sources on the web about film, television, and entertainment.
You can view all of his work on his website, www.thereeljames.wordpress.com