Low ratings. If not enough people were watching, the network or studio might not have wanted to keep investing in it to finish the story. It's all about the money in the end. If it's not making a profit, they'll cut it short.
The manga itself might have been still ongoing while the anime was being made. And the anime team decided not to wait for the manga to finish before starting the adaptation. So when they got to a certain point, they had to end it without covering the whole story. This can happen when there's a desire to get the anime out quickly to capitalize on the initial popularity of the manga.
I suggest checking out official manga subscription services. For example, Viz Media often has licensed manga available for reading. Also, some libraries might have digital access to Bleach manga.
One reason could be simple curiosity. Naruto might be interested in seeing how fans from the Bleach fandom imagine different storylines. Another reason could be to gain inspiration for his own ninja world. Since Bleach has unique concepts like Soul Reapers and Hollows, Naruto could be looking for fresh ideas that he can adapt to his own battles and relationships in Konoha.
One reason could be for comedic effect. Diapers can be used in a humorous way, like when a character is put in an embarrassing situation related to diapers, perhaps a clumsy character accidentally wearing one or getting diaper - related tasks wrong.
Character development. Completing the story often means your character gains new skills or abilities. It's a great way to make your character more powerful.
One possible reason could be to gain more power. In the Bleach universe, the dead often possess unique powers or knowledge. By raising the dead, Ichigo might be seeking to learn from them or use their power to fight stronger enemies.
In some cases, it could be a part of a unique world - building concept. If the anime is set in a world where magic or some strange phenomenon can turn people into different forms, a girl turning into a baby - like form with a diaper could be just one aspect of that strange and interesting world. It can add a touch of quirkiness to the overall setting of the anime.
One possible reason could be that Tsukishima is under some sort of mind control or influence from a more powerful and malevolent force. Maybe he has been deceived into believing that Ichigo is a threat to something he holds dear.
Well, the Bleach anime story is really exciting. It begins with Ichigo's ordinary life being turned upside down when he gains Soul Reaper powers. He has to balance his normal life as a high school student with his new duties. In Soul Society, there are political intrigues and power struggles. Ichigo and his friends face powerful enemies like the Espada, who are Arrancars with great strength. And as the story progresses, Ichigo discovers more about his own powers and his connection to the Soul King.
A third theme could be discovery. The kid in the story might be exploring the world of bleach, learning about its uses and effects. This could be a journey of self - discovery as well, as the kid discovers things about himself or herself through the exploration of bleach - related situations.
In my opinion, both have their merits. The anime brings the characters to life with animation and sound, but the manga allows for more imagination and detail in the panels. It really comes down to what you value more in your entertainment.