The problem with Pokemon as an anime is that unlike Shonen series like Naruto, One Piece, or even f'ing Yu-Gi-Oh, Pokemon's target audience is little kids. Sure, the other mentioned anime series also target little kids (One Piece and Toriko as anime are DEFINITELY little-kids-anime, and all the blood/extreme violence/swearing of the manga gets censored out of Jump series before they hit the TV), but they're based on manga meant for teenagers.
What does this mean? Well, for Yu-Gi-Oh, it meant that the original anime series could not continue indefinitely no matter how much merchandise and trading cards they had to push. Yu-Gi-Oh the manga was a Jump manga read by middle/highschool students-- and when your audience aren't little kids, you need at least a start, development, and conclusion to your story. You also can't inexplicably erase all the character development and maturity of your protagonist at the beginning and end of each season. Basically, you're reigned in to actually making a story that has a real plot. (and then you sell out the rights so that someone else can make the kiddie-targeting garbage "sequels" that keep selling more trading cards)
Now, if you're sesame street or Barny the dinosaur, you can pretty much keep doing what you've been doing for years and years and years until you get usurped by someone else doing it better.
Than, if you're Pokemon, you don't even need to worry about that. You just have to worry about brain washing the next generation to watch until they out grow it so you can brain wash the next.
Also, anyone know a different franchise that could make 15+ movies and have them all be successful on the big screen? OMG... and yes, many Japanese parents actually ENJOY watching the movies with their kids (I enjoy them too actually... the movies, unlike the anime, actually have plot... and animation quality...)