Shows like Gotham and Smallville had way more episodes per season, and tried to remedy this with "monster of the week" episodes. And for shows that come out each week instead of in one binge-able bundle, this helps, because you're never around for long enough to think "Huh, this small Kansas town sure does have a lot of mutated creeps in it." But in this case, it's the human subplots that suffer. You motherfuckers don't know how good you have it. I spent years watching Clark Kent stumble around telling Lana Lang how much he loved her. YEARS. I could've hung out with my family or played with my dogs or gotten hobbies. I could've had a life.
Obviously, we're a little spoiled by other mediums. Superhero movies tend to be around two and a half hours, which is long enough to tell a satisfying story, but short enough that your bladder doesn't combust in the theater. And superhero cartoons tend to be around 20 minutes, while comics tend to have around 20 pages. But in the case of live-action TV, it feels like the storylines are written and set in stone before the number of episodes is given, forcing writers to say "Fucking 13 episodes on six episodes' worth of plot? Ninjas it is, then."