So how exactly does Warner intend to put out a JL movie to compete with the Avengers, when they have not put in the effort to construct a franchise to compete with the films surrounding the individual members?
Marvel generated interest for the ensemble film by establishing the various characters for the viewing audience (particularly Iron Man and Thor, who were not nearly as popular as Captain America or The Hulk). Plus it gave audiences a base understanding of their powers so they wouldn't have to waste time explaining it in the group movie.
Warner apparently intends to trot out Superman, try and reboot Batman on the heels of an incredible trilogy for which I do not expect them to find a comparable actor OR director, and then expect people to care about Aquaman, The Flash, Green Lantern et al without first telling people why they should bother (not to mention simultaneously encouraging them to forget the Martin Campbell debacle for GL ever happened).
And also, they'll have to write a screenplay to compete with Joss Whedon, God of the Nerds. [http://youtu.be/QDajL441mZc?t=8s]