Don’t get me wrong, I like the occasional shounen bash because they’re violent and visceral, but seriously, series like Naruto and Bleach suck.
My theory is that in part, the model for shounen manga/anime creations like Bleach and Naruto are not necessarily story-driven. Naruto and Bleach are completely self-sustaining as long as there’s enough people to watch it, so I doubt there is an actual end in site as long as they sell. This reduces their structure to a “hero fights, loses (or gets weaker somehow), gets stronger, fights again and wins” deal, which can propagate infinitely, not a joke, until sales start to dwindle. It feels like that is the only reason that these series have to end (or the author gets burned out on his own increasingly shitty material…) and there is no way that as a whole something like this can be superior to a story that is conceived as a whole with an ending to write toward.
Dragonball is the prime example of this, I think. Although interesting in fast forward, the only reason Goku can beat the continuously stronger enemies is the fact that he basically gets new Super Saiyan abilities with every new one, nevermind his determination and crap. I mean, they get to Super Saiyan fucking FIVE at the end of GT (although I guess that wasn’t related to the manga). If they made a new series there would have been six, seven and eight for sure, but the falling fervor for Dragonball and the fact that Akira Toriyama had nothing to do with GT kinda dampened the necessity for new continuations.
If you’re still not convinced, then answer why Naruto had a fucking year and a half of fillers and Bleach had some crappy Bounto arc that they now have to write random references to despite them not existing in the original manga. It wasn’t so that the source material could get ahead – if they wanted to stay focused they could have just stopped the series and then continued after a season. Unfortunately, the primary point of these series is to sell, not to tell a story, and we get a half-assed arc (or a year-long one) whose quality pales in comparison to the already-diminished status of the actual thing. And that equals money, but it definitely won’t equal quality.