It's not called Batman v Superman: Dawn of Justice just for the hell of it. If you give your movie a subtitle that so heavily points toward a sequel, you better deliver. However, given the stuffed nature of a film that we already know features Batman, Superman, Wonder Woman, Cyborg, Lex Luthor, Alfred, Doomsday and Aquaman, there may not be enough room to make good on the promise of justice during the main run time. Luckily for director Zack Snyder, he doesn't need room. Post-credit tags exist for a reason - to show us things that didn't fit in the main feature, or to show us things there weren't space for in the main feature. Imagine the screen going black, and a musical cue swelling up to reveal all six members of the Justice League stood side-by-side, possibly observing a wrecked Gotham city and swearing vengeance on the villain that caused it? The crowd would go wild. Also, Dawn of Justice. Ahem.