What went wrong with Bleach.
There are many things that have gone wrong in the Bleach manga series. Plot holes are frequently cited as the greatest problem. Lack of plot; and character development; are also issues. There are nonsensical characters introduced, pointless arcs, cumbersome execution of storylines and pointless dragging out of fights. Chapters that have no real purpose, comedy that just isn't funny. People rant about it on the internet all the time; I've yet to see one attempt to make sense or structure of the problems.
But through all this chaos, let's try to make sense of the big question: why does Bleach suck so very badly?
I'd break it down into 3 points, the magic system, the characters and the plot. I'll be referring to them with reference to Sanderson's Laws, and then some additional comments. Who is Sanderson? Brandon Sanderson is a Fantasy author. He finished off Robert Jordan's Wheel of Time series after the latter died, and writes several series'. He isn't without fault, certainly I get bored by some of his too clear-cut characters and clean plot arcs, but he comes up with the best magic-systems. Period.
How to read: Look up the law before reading my explanation, it's critical that you know how the law works if you're going to understand what I'm getting at.
Problem 1: The magic system.
Sanderson's First Law - An author's ability to solve conflict satisfactorily with magic is directly proportional to how well the reader understands said magic.
In Bleach, the magic system is shinigami/quincy/hollow/fullbring powers and whatever the heck Orihime has. A hell magic system is alluded to but is never explained outside of a shockingly awful non-canon movie.
We pretty much have no idea what the laws of magic in this series are, just that some people have differing abilities of greater or lesser power. At the beginning there did seem to be groundwork for a few laws, such as Renji only having a few swings with Zabimaru before he had to reset. That went out the window pretty quickly. Basically there's some rhyme and reason in the Soul Society arc, then as the story goes on it gets more blurry. In other words, the magic system actually gets softer as the series goes on. "Soft magic" isn't necessarily a bad thing; they invoke a sense of wonder in the reader. But they can't be used to resolve the major plot points. At least, if you do do it, it must be an extremely rare occurrence. When you are relying on soft magic to solve all combat problems, which happens almost every chapter in Bleach, it's ridiculous and completely lacks tension. Bleach needed to have a very "hard magic" system with clearly defined laws and limitations for the battles to mean anything. Fullmetal Alchemist is an excellent example of a manga that got this right.
Additionally: Orihime's powers are really, really dumb. And what the heck was up with Uryuu's soul energy tubes/capsules, and why hasn't it come up again in the Vandereich arc? I tried to come up with some way to use them in my story; ultimately I came up short since there was simply nothing to work with. I'm not even going to go into how little the Vanderreich powers make sense, since they're all Quincies and should all be to an extent clone copies of Uryuu. And the less said about the Fullbringers the better, though why the heck would Chad's skin be the focus of his power? His pride and joy was his medallion from his grandfather.
Problem 2: The characters.
Sanderson's Second Law - Limitations Powers
This one's pretty easy to understand. Ichigo is far more interesting as a character when he's having anger issues, overconfidence and trouble controlling his power level than he is as his post-Aizen version of a soulless demigod. His dark/hollow side was very interesting, why hasn't that come up again? Rukia was most interesting when she lost all her powers in the first arc, and hasn't been the same since she got them back. This isn't limited to the heroes either, which is something often forgotten in manga series'. Byakuya was most interesting as a decent guy who was bound by the law to be Ichigo's enemy. Aizen was no longer interesting as a villain when his power level exceeded 9000!
Additionally: A core ingredient missing from almost every character in Bleach is their motivation to do stuff. More specifically, they don't have multiple and sometimes conflicting motivations, like real people and interesting characters do. Ichigo wants to protect stuff and… nothing. Hitsugaya wants to defend Soul Society and… nothing (besides looking adult at the same time). Tite Kubo doesn't seem to have a very good grasp of characters outside of their eccentricity (which, while on point, gets old quick). He introduces characters, has no idea what to do with them once he's played with them once, and then shoves them into the background to introduce more. The toy box is overflowing, and it's taking over the floor. What was needed was some character development; which would be a byproduct of them having actual motivations; and yes, some character death. Nizuma said it in the entertaining (though limited by its subject matter) series Bakuman, create characters that move on their own!
Problem 3: The plot
Sanderson's Third Law - Expand what you already have before you add something new.
Here's the thing: Bleach has a lot going for it in terms of ideas and the world. It's all hinted at, and then never fully addressed. And that's a problem, since without proper expansion an idea just becomes a loose thread. This is by far the biggest problem in Bleach. Kubo barely ever expands on anything; he just throws it all on the table and hopes it makes cake. Just like he will introduce a character and forget about them once they've done what they were supposed to do, he does the same with ideas and world-building concepts. But here's the thing, leave all these threads hanging and sooner or later you'll tread on similar ground and contradict yourself. And that's how plot holes are created.
This actually started way back in the Soul Society arc, some concepts were explained, but not enough and certainly not in enough detail. By the end of the arc there were already some definite problems, but certainly with proper direction for the arcs following this could be smoothed over. That's not what happened, and by this point the plot holes have reached critical mass. Nothing makes sense anymore, and I get the feeling that even Kubo has stopped trying to make sense of it.
Additionally: Sheesh. There are so many problems with the plot. It's obvious at this point that Kubo should have hired someone to do the plot right after the Soul Society arc, when it was still salvageable. There really is no saving Bleach now, and I wouldn't be at all surprised if they rushed the end or even finished it without ending properly. It happened recently to a manga I used to follow, History's Strongest Disciple Kenichi, and it was making all of the aforementioned mistakes. That said it's more likely that the goodwill it built up in the Soul Society Arc will allow it to finish on a whimper.
Some of these problems come from the fact that it is a manga, which doesn't lend itself well to plot, but it is a problem that can be overcome. Some series' manage to be very strong on the plot, like the excellent Death Note.
A few more notes:
Kubo's artwork is excellent. I'm not an artist myself, but even I can appreciate it. If only it would be linked to a better story!
Some of the problems of Bleach are conceivably because of its non-battle manga start. All of Ichigo's human friends don't transition well into their new roles, and only Ishida is passable. Ichigo himself wasn't designed as a Battle manga hero, and while a bit of development to his character would have conceivably fixed that; Kubo doesn't do character development well.
Tite Kubo isn't bad as a world or character designer, he just isn't particularly deep. This wasn't a problem early in the story, but it became one as the story continued. If he does come back to writing manga after taking a holiday after Bleach ends, he'd better find an author to work with. I'd recommend Sanderson. The incredible chaos Kubo brings plus the overly clean order of Sanderson could create a masterwork. Or a mess. Either way it would be interesting.
PS: Feel free to spread this if you liked it. Just as a courtesy, please put a link to this page wherever you post it. Who knows, maybe it will actually get to Kubo!