Its not just the CN. There are a lot of good cartoons that have finally ended. Phineas and Ferb ended last year, and Gravity Falls just a week or so ago on Disney. Nickelodeon has nothing. CN has only The Amazing World of Gumball.
The thing is, the CN used a tactic others don't seem to try. They bring out a ton of new shows all at once. They've always done this. And they don't pull something until the show has gone through at least a season.
Teen Titans GO! is honestly stupid and has no real points, but it is all together better than others I can remember. Its sad that they used characters from a EPIC show (that needed a better ending than it got) and made the story a jumbled mess. Terra is now a villain? Raven and Beast Boy? Starfire doesn't like Robin? I bet anything, that if they took the time just to use the same models but make it more of a parody to Teen Titans by making them a off brand, then it might had been something. People don't like watching their favorite characters act like fools for laughs. (If you haven't seen Wabbit! its sort of what I feel is going on here.)
Cartoons don't always need wit and humor, right now CN has no action adventure (which will then get a ton of shows about adventure).
I remember the day that Naruto first aired on CN... it was the first day many of a new generation got introduced to Japanese cartoons. They barely censored anything. Even said "Bastard" and had perverted jokes. It showed what Americans fail to do, and that is to get a story together and make it into something. Something Nick can only do once... (if you don't understand, I'm talking about The Last Airbender... Avatar).