By giving these characters quick, but poignant cameos in Justice League, future films won’t have to work nearly as hard to establish their existence in the DCEU.
Logistically it wouldn’t be tough for Justice League to provide a few quick cameos, and the payoff would be well worth the effort.
The recent announcement that Arkham Asylum would appear in Justice League has us all sorts of excited for the upcoming DC adventure.
It’s important because it affords the DCEU the opportunity to establish future characters and villains that will properly debut further down the line, most notably in Batman’s corner.