4. It Can Set Up New Elements For the Justice League Movie
Probably one of the coolest parts of Marvel's Phase 1 movies was the after-credits scene. We didn't know much about what the outcome (the Avengers) will be, or how the story would develop, however it was really nice to see a little hint at what he had in store for when the movie came out. By the time it did I was really happy to see that all the pieces got together and that the end result was everything promised in those few seconds and more. DC doesn't necessarily has to do those things in order to tease some of the elements that will appear in the Justice League film, it can take a different approach, like mentioning some of those things on the movies or just showing some of them in some episodes of Arrow. For example, let's consider that someone is helping Darkseid reach mankind in the Justice League movie. Maybe they can tease that event by having that someone on Arrow doing some evil things and completing his plans before disappearing, leaving Oliver really concerned about what's going to happen. Something like that would be good enough to set-up possible villains or plot-points of the movie, and it will be really cool to see them on screen.