The animation in Rise of the TMNT is very good.
EDIT:
All I could find is an AMV but this is still a good demo of the show's animation
I feel like I need to clarify something that I may have expressed poorly. I'm not saying these newer shows are bad or not entertaining.
Animation is a volume business. Get the most money for the least expense. in animation this is quantified in new art per frame. If you can find a way to copy the same drawing into 30 frames, you've used up 10 seconds of show time with no effort. Do that 30 times in a show, and there's several minutes of an episode. This can be done by reusing the same frame in different scenes (and in different episodes) or it can be done by using the same frame for 1.5 seconds several times, or it can be done by interchanging a handful of of frames repeatedly (arms up, arms down, repeat every .5 seconds for 2 seconds, to show character frustration). Or of course all combinations of these.
This didn't used to be how animation was done, but it has become more prevalent since The Flintstones, for instance. And artists have ingeniously figured out how to make their work stylistically distinctive so that this is not so apparent. That is to their credit.
But that distinctiveness will be hit and miss. You'll have Power Puff Girls, Teen Titans Go, Superman TAS, and now Aquaman. What you prefer is what you prefer, but that doesn't make it entertaining or not entertaining. It does make the animation less and less fluid.
How much? Was there a dip in quality? And if not, how profitable were those after-theatrical shorts?
Here's the thing, the Looney Tunes for tv were the very, very, very early days of television. There were only a few channels - literally like 3 or 4. And there weren't many shows because tv was new. Less competition, more of the viewership. And to top it off, because TV was new everything was a learning curve, including how much could be spent on aniation for this new medium. There's a reason all tv animation since isn't "as good" - they figured out their budgetary restrictions once things became more settled. Hence why say 70's era Tom and Jerry isn't as good as the classic era. It's all about the budget.
Your argument is that no animation with non-theatrical budgets are good, which is unfair. If you stop comparing them to theatricals and early tv which still had the oomph of the theatricals behind them, and compare them to all realistically budgeted shows since, you can make a better comparison.
It's like comparing most classic tv with classic films - the films are better. Does that mean no tv show ever was good?
Kirby101 is correct. All those classic animated shorts from the studios were done for theaters. Cartoons, live action shorts, and newsreels used to be shown before the movie. Cartoons lasted in theaters until the late-1960s/early-1970s.
The first Tom and Jerry series for TV was 1975's The Tom and Jerry/Grape Ape Show. Every Tom and Jerry short before that was produced for theatrical distribution. Same goes for Looney Tunes. Every LT or MM short from the 1930s to the 1960s was for theaters.
Anyway, in my OP, I'm really commenting on the horrendous character designs. I say "Bad News! It looks like THIS." Not "animated like THIS."
No matter how well or poorly it's animated, the art style is still poorly done kiddie crap. The older superhero shows had bad animation in the days before it was farmed out overseas to save costs (which resulted in allowing for better animation), but the character designs were often quite nice.
Designs and animation aren't the same thing. The old DCAU had simpler styles than the Marvel cartoons of the era - X-Men and Spider-Man The Animated Series. The designs for those shows were very good. But compare their stilted, awkward movement to Batman The Animated Series and the difference is clear.