I wonder if the series could have worked in such a way, like...
Episode One - Batman teams up with Green Arrow.
Episode Two - Green Arrow teams up with Black Canary
Episode Three - Black Canary teams up with Zatanna
Episode Four - Zatanna teams up with Etrigan
And so on, and so forth. Various heroes could make return appearances (for example, Green Arrow would need to come back and team up with Green Lantern!).
Anyway, I guess I can't complain too much - We got 65 episodes filled with some of the most amazing and obscure heroes and villains from within the vast history of the DC universe.
When we have another television series willing to go as wacky as BatApe or teaming Batman up as Uncle Sam in one episode, then giving us something as awesome as Chill of the Night or the entire Starro sub-plot later on... well, it just doesn't get any better than that.