I guess the people that make movies have a stronger union than the people that make TV shows then.
Star Wars is another example of a movie with multiple characters that didn't need an individual movie to set them up. It told a great story and we got to know the character that way. And WB did have solo movies
for Batman, Superman, Wonder Woman prior to Justice League but it still didn't help. Having Aquaman, Flash, and Cyborg with solo movies first wasn't going to make that much difference. If Batman, Superman and
Wonder Women didn't draw people in, why do you think knowing the intimate details of Cyborg would? What more did we really need to know? He got in an accident and his father found a magical device that turned
him into a half robot/half man thing.