Seeing as Arrow had to kill off Deadshot because of the Suicide Squad movie, Cyborg not being in the Titans is likely because he's already in Justice League. Audiences are too stupid to be able to comprehend multiple live-action superhero properties. I'm only half joking here, there are a depressing number of people who get confused by which characters belong to DC or Marvel. Which meant Titans lost their token bla- er, I mean black representation. What to do then, bring in Bumblebee? No, don't be silly, just chance the race of one of the established characters. Can't be Robin, too iconic. Can't be Beast Boy, because having a black character named "beast" and turn into a gorilla would be problematic. Can't be Raven either, because having a black character be the spawn of a demon is also problematic. That just leaves Starfire. Don't know why they went and made her look like a cheap prostitute, though.