8. It Will Undermine The Dark Knight Rises
The Dark Knight Rises managed to bring the Batman saga to a stunning, emotionally wrought conclusion, in which Bruce Wayne retired like he always wanted to, and an optimistic young charge, John Blake, took over his lead. To bring Bruce Wayne back for the Justice League movie spells trouble, because it's going to undermine everything that Nolan and Bale worked so hard to achieve. I can see it now; don't worry Alfred, that glance in Florence meant nothing. Kick the orphans out of Wayne Manor, tell John Blake to get packing and bring Bruce back from legal death so he can go hang out with a bunch of extraterrestrial superheroes. There are very few ways for Nolan and Bale to make this work without cheapening Wayne's exit at the end of The Dark Knight Rises. Even if he was brought on in an advisory or strategic role only, it would compromise the fact that Bruce is meant to be out of the game and living a happy life with Selina Kyle.