To give all examples we start with the Dragonball franchise which has Dragonball which was 153 episodes long and was accompanied by 4 movies, Dragonball Z which was 291 episodes along with 15 movies and 6 OVA's & TV specials, Dragonball GT which although not officially cannon was still 64 episodes long with 1 special, and now we have the Dragonball Super series which has 128 episodes currently and is planning to have I believe 3 or 4 more to go; that is a ridiculous amount of around 636 episodes, 19 movies, and 7 specials.
Next we move on to the Naruto franchise containing the original Naruto series which has 220 episodes along with 3 movies and 4 OVA's and specials, then the Naruto: Shippuden series which has 800 episodes, 7 movies, and 7 OVA's and specials, and then the Boruto: Naruto Next Generations series which already has its own movie and 1 OVA along with 43 episodes and counting. That is more than Dragonball and sits at a ridiculous 1,063 episodes with 12 OVA's and 11 movies and counting as Boruto is not done.
Finally we move onto the largest franchise and most popular Shonen of all, One Piece. The show is CURRENTLY at 826 episodes and continuing on which is ridiculous as it is more than 4 different Dragonball series' and nearly close to all 3 Naruto series combined. Also right now has a total of 13 movies and 12 OVA's & specials. It stands as the longest standing singular Shonen series and apparently only seems like it will finish its anime version when the manga is complete as they intend to animate everything.
As of now Bleach sits at 366 episodes with 2 OVA's (The Sealed Sword Frenzy and Memories In The Rain) and 4 movies (Memories of Nobody, Diamond Dust Rebellion, Fade To Black, and Hell Verse). Which still SOUNDS like a lot but in comparison to the other "Big 4" Shonen anime it is peanuts. Also Dragonball and Naruto have their entire manga's animated and One Piece plans to continue animation until the end of the manga; they are not bothering to do that with Bleach.
They stopped at the Fullbringer Arc and left out one of the coolest ones, the 1000 Year Blood War arc, which as of August 2017 Tite Kubo finished writing and drawing his manga. While many people think I may be a tad bias towards Bleach with it being one of my favourite anime/manga series, I'm looking at it objectively from its perspective in anime & manga history.
I think Bleach deserves to have its last arc animated for several reasons. Also, there will be SPOILERS in this article for the 1000 Year Blood War arc, so if you haven't read the manga to this point in physical form or up until its completion digitally thanks to fan translation, then stop reading this and finish Bleach because it's great. However, if you go forward just know that I'm going to bring up certain things that are in this arc of importance to the arc and why it should get animated but might ruin you if you are spoiler free.
Now many people will point out Bleach's declining sales near the end of its run to why it doesn't deserve its last arc to be animated but it didn't evaporate in sales, they didn't drop, it was still outselling manga like Boruto and they still decided to not only do a feature film for that but to do an anime afterward. It is a shame to see a manga series that was and is so beloved by so many and considered one of the biggest and most influential Shonen ever, part of the Big 4, not be treated as an equal. Providing animation to the final arc would give Bleach the same treatment as Naruto, Dragonball, and eventually One Piece. They all deserve the place they hold in manga and anime history so it makes sense that seeing the series conclude would be best for it.
It was touched on again in the anime only Bount Arc, the story of Quincy and their slaughter, how as "The Last Quincy" that Ishida should hate the Soul Reapers as much as the Bounts do. Not that I want to bring up that arc too much with how garbage it was.
So every arc and every enemy as a "theme" I call them. The Shinigami are Japanese, the Espada are Spanish, and the Quincy are incredibly steeped in German themes. From their names to their techniques to their "divisions" (similar to the 13 Court Guard Squads) everything about them is Germanic in nature, however it isn't just normal Germany more of Nazi Germany. The Quincy are like the Nazi's in nature.
When they lost to the Soul Reapers 1,000 years ago the Quincy retreated to the one place the shinigami wouldn't look, The Soul Society. It was there that they set up what is called the Wandenreich/Vandenreich (Invisible Empire) and soon after they regained enough power and Aizen was defeated the marched on Hueco Mundo an annexed it and took many Arrancar left there under their control.
Standing above all of them is their leader Yhwach (or Juha Bach), who is an infallable leader who wants to destroy the Soul King and eliminate the boundries of life and death.
There are normal soldiers in the Vandenreich known as Soldat (Soldiers or Divine Soldiers) but there are the elite few, and again drawing Nazi comparisons very similar to an SS style of soldier, the Sternritter. All of whom fufill different roles in the Quincy hierarchy. The head commander of the Sternritter is the incredibly strong Quincy, who most expected to take over for Yhwatch, Jugram Haschwalth. The next four: Pernida Parnkgjas, Askin Nakk Le Vaar, Gerard Valkyrie, and Lille Barro are all the Elite Guards who protect Yhwach with their lives (not that he needs it). The other 21 members of the Sternritter are all as strong as high rated Arrancar or around Lieutenant or Captain Level Soul Reapers.
Between one of his best friends being a part of the enemy, to his newfound heritage, to the incredible strength of the enemy this makes the Quincy the toughest fight for Ichigo Kurosaki and company. It would make the wait well worth it to see these interesting Quincy characters "brought to life" on screen.
Well, we find out that a Hollow is kicking the shit out of Isshin Shiba and he's truly unable to properly fight back against this Hollow and then he is saved by this beautiful and badass Quincy girl named Masaki Kurosaki. The Hollow attacks her and it gets complicated as to what happens so I won't explain everything; Isshin takes her to Urahara and says he'll volunteer to lose his powers to help her from dying. He does and long story short this badass Quincy girl who took down a Hollow that was kicking the shit out of Squad 10's captain is Ichigo's mom. Oh also that Ishida's father had a huge thing for Masaki but because he saved her life she ended up falling for Isshin.