The less than two-hour runtime for Justice League is shorter than Wonder Woman (2h 21m) and Joss Whedon’s blockbusters at Marvel, The Avengers (2h 23m) and The Avengers: Age of Ultron (2h 22m). Comparable runtimes would be Marvel’s Guardians of the Galaxy (2h 2m) or even Thor: Ragnarok (2h 10m), which are comedies, or Doctor Strange (1h 55m). Marvel’s recent Spider-Man: Homecoming came in longer at 2h 13m, and Guardians of the Galaxy 2 at 2h 18m. It should be noted the 3-hour cut of Batman vs. Superman was a lot better than the theatrical version. Reportedly, WB wouldn’t allow Snyder to go with the longer cut as well.
Hopefully, the 2-hour cut of Justice League is still decent enough, but I know I wouldn’t mind a longer Director’s Cut released eventually. I’ll also add the problem with Batman vs. Superman wasn’t that it was too long or too dark, it was the writing and story.