9. It Improves The Chances Of Success For Individual Installments
With Marvel's Phase One to their Cinematic Universe, they took a huge gamble and did things "the proper way": they focused on individual stories with individual heroes, co-mingled them to a limited (yet successful) degree, and delivered the goods with an all out combo punch of a film that tied everything together. Now practically, that is the right way to do things. Marvel could afford to take their time and work on their long game, slowly and lushly building the world around The Avengers before any proper avenging could take place. Unfortunately, DC doesn't have the luxury of time. DC has been in the comic movie game longer than Marvel, and yet they've still
had their rears handed to them at the box office. While The Dark Knight Legend may have been a heavier hitter than any singular installment of the Marvel canon (with the exception of Batman Begins, which is handily beaten, in comparative terms, by Iron Man), Marvel has been more consistent, more varied, and more successful with their film operations. DC, on the other hand, is the franchise of broken promises, failed dreams, and overall instability. They need a silver bullet to wipe out the Green Lanterns and the Superman Returns of their canon. It's wiser of them to start with the big guns and re-introduce us to characters we already know and love, as well as some who haven't gotten proper big screen lovin'. With Justice League in the books, a Flash movie would be less of a gamble. Hell, even Aquaman could benefit from a Justice League win, as people would be more inspired to see the origins of the characters they've already seen in action on the big screen. Instead of slowly building an audience for the combo picture, you're rapidly building an audience for each successive solo picture, which in turn could amp up the grosses to each individual franchise, and thus give Marvel a run for their money.