It's what keeps the show going. Did you expect them to throw the Light into prison?
I liked the ending. It was sad, plot-wise. Some folks didn't spend enough time together before separating. Most of the threads tied up well.
It would've been nice to have the ending be a 1-2 hour special. See more of the Black Beetle fight, see some of the Runaways in action. I initially thought Vandal Savage would threaten Rimbor with destruction unless the JL was executed, and a fight would break out, but alas, the story still had the seeds of Season 3. Seeing the GL corps taking on the Reach would've been cool too.
As for the sudden appearance of Trolls, I guess My Little Pony must've wrapped up it's season, so haters gotta find something else to hate. Of course it's kind of crazy to have sidekicks taking on big baddies, but it's a cartoon. It's suppose to be fun. But with just enough adult themes and darkness to not be irritatingly "fun" and wacky like the Nutra-Sweet of Teen Titans of old. Which yes, was enjoyable, but not every cartoon has to be hip and ironic.
Wanted to Red Tornado in action!