The problem is that WB saw the success of the "serious" or "dark" Nolan Batman films and have decided that's what audiences want from all comic book films.
Justice League will be the same as Man of Steel; boring. Not only that but we are getting characters who have never even been introduced before just thrown into a 2 hour film together which is a recipe for disaster when it comes to character development.
Bingo. Going 'dark' works with Batman because he is by far one of the darkest super heroes in the DC universe. Personally I'm kinda meh on the Nolan films anyways but the point remains the same. Superman isn't supposed to be dark and edgy. He's Superman, he's the antithesis of that. He's a symbol of all that's good in the world, the unstoppable force of good against evil.
Also, it's obvious that the only thing WB learned from the Avengers build up was that a big superhero mash up movie CAN make big bucks. Unfortunately they seemed to have skimmed over the fact that Marvel spent literally years building up to it by giving practically every character their own movie and/or cameo. Who have had movies in this? Superman, Batman will in the Batman vs Superman movie, and Wonder Woman who is just being shoehorned in to the movie. WTF!
Wonder Woman is one of the biggest parts of the Justice League but she can't even get her own movie? What? Is pseudo-Greek mythology not big enough for a motion picture? Norse mythology seemed to work just fine. They could make an amazing Wonder Woman movie and that's not even mentioning all the others. Green Lantern, Aquaman (they could go REAL dark with Aquaman since he doesn't have a no-kill rule), Flash, etc. So yeah, this is gonna bomb.
