The thing is more that the Pokemon anime makes its profits on the back of the overall franchise popularity at this point rather than any of its own merits as a show. Take something like Teenage Mutant Ninja Turtles. Each incarnation of that show has come out well after the franchise was established, but despite being very obviously merchandise driven the show isn't afraid to mess with the status quo over the course of seasons. I only saw some of the 2003 incarnation in particular, yet in the course of 2 seasons I can recall major shake ups such as: shift from episodic to arcs (beginning with the Shredder), change from major villains and absence of major characters (Splinter's disappearance and defeating Shredder), drastic change of setting (they ended up on Alien worlds at one point), big twists/reveals about old characters (the Utrom's ties to their origin and Shredder), just to name a few. This is arguably one of the longest standing merchandise-driven properties, so things like TV adaptations have every excuse to lean on brand power, yet while the actual quality can be debated in circles, it's hard to say the shows were not at least trying.
In contrast, Pokemon has been on virtually the same formula since its debut, with a minor change when Gen 3 introduced non-Team Rocket syndicates: Ash goes to region, Ash challenges Gyms to compete in Pokemon League, Ash and friends stop villains world conquest schemes, main Team Rocket trio provide wacky hijinks trying to steal Pikachu. Beginning Gen 3, add "Female Player stand in competes in secondary competition as foil to Ash". When I saw Serena, I didn't think "what is this character going to do", I just thought "what was the sidequest she's going to advertise". Even in Gen 6, where they took some risks along the way, the ending clearly indicated there's no intent to even slightly change the status quo, with Ash not only losing the League again, but Greninja, potentially one of the biggest potential symbols of Ash's growth as a trainer, departing in a capacity that makes it even less likely to return than any of Ash's other "put on a bus" members.
What I'm getting at here is that while a show can be made for profit, even in the most "for profit" cases that doesn't give the creators an excuse not to try and let the show grow in some capacity. Hell, I can also bring up Friendship is Magic, but I don't follow ponies so I don't have anything to say besides that as another example of merchandise driven having a fanbase regardless.
The reason the state of the current anime bothers me is that the games and manga clearly offer enough material to do a story with the standard sense of progression and quality, whether with one character or with each region's own hero, but at this point they've dug themselves so deep into a hole with the Ash status quo, they probably can't get any faith in the show as a TV property bar pulling it up by the roots and starting a new one: Origins and Generations got a lot of hype and decent reception, and I recall in spite of their problems one consistent point of discussion was how they still handled things better than the main anime. Shows like the Simpsons and South Park are designed to be disconnected and episodic for gags, inevitably they'd get stale going on for so long when they run out of jokes, but the Pokemon anime has its stories written out and is not in a format that necessitates or even favors keeping a stringent status quo.
