Here's the thing.
While I totally feel that Spongebob takes up waaaaay too much of Nick's schedule, they've really been railing it to their animated shows since the last decade. And for the exact reason you think. TMNT is thankfully around mainly due to toy sales. I was very very worried about the characters when Nick bought them back in 2009, only to be pleasantly surprised by a great TV show and a toyline that managed to have a better balance of character variants and villain characters, something the 2k3 line lacked and eventually was undone by. Suffice to say, while 2k3 was going the comic book route and not putting a crapload of cartoony mutants into the series, Playmates felt that the line needed as many really bad variants of the turtles as possible, while shortpacking anything that wasn't a turtle variant. That lead to poor distribution with some figures being impossible to find while wacky sports Turtles, completely in the WRONG tone of the serious series, pegwarming. Then there was the movie line that took over the cartoon one. Anyway, uh... the new show is not afraid to make mutants serious and silly at the same time, leading to a better balance of characters and even some rare show accurate variants that manage to be fun on their own.
Back to Nick's cartoons, I get the feeling that every cartoon they've produced since the past decade that isn't Spongebob or freaking lucky enough to find an audience, albeit briefly, they wanted to fail desperately since they weren't the hip live action shows that Disney was doing at the time. Even today, you hear more news of live action show premiers than cartoon ones. So Nick either shoved the cartoons to weird hours to sabotage the ratings (El Tigre) or all the sudden decided they didn't want and stopped running, even with a season's worth of episodes left (T.U.F.F. Puppy). All because they couldn't make terrible soundtracks with the stars of the shows singing the most generic pop music ever. Consider Spongebob didn't even become popular for 2 years after the show premiered. It's obnoxious that they feel they need to get a hipper tween demographic with live action shows far more juvenile than the animated series they have.
I'm hoping Harvey Beaks gets an audience. And not the "we love it at first, but it's not a cliche ridden, by the numbers kid com, so...." way. I heard Sanjay and Craig was one of their most watched show. Got renewed to season 3... So they put it on a nice several month hiatus where they didn't even show the reruns (outside of Nicktoons). Yep. That's really how you can tell a show's successful. S&C became one of my new favorites in a short time, and it sucks that, even with high ratings, a bunch of doofy kids doing the same thing doofy kids always did in those sort of sitcoms is considered a higher priority.