Well, it could be that she simply doesn't have the time or inclination. Fanfiction often takes the characters in different and sometimes wild directions. Kishina, as a part of the original Naruto universe, might be more concerned with the integrity of the core story. And also, she might not be aware of the existence of fanfiction at all. After all, not everyone in the Naruto world is tuned into the fan - created content outside of their own story world.
The fanfiction changes the relationship dynamics within the Naruto world. Usually, Konoha is at the center of Naruto's universe. But now, with Naruto not caring about it, other elements like his personal relationships outside Konoha or his own self - discovery become more prominent. It shifts the focus from the village - centered story to a more individual - centered one.
One possible reason could be that Naruto has been mistreated by the villagers in Konoha for a long time. Despite his efforts to gain acceptance, if he's constantly faced with rejection or unfair treatment, it might lead to him not caring. For example, when he was a child, many villagers shunned him because he was the host of the Nine - Tails. This continuous negative experience could build up over time and cause him to lose his sense of loyalty to Konoha.
She might be too busy with her own life in the Naruto universe. There are so many things like battles, relationships, and her own growth that she has to deal with. Fanfiction is just not on her radar.
One interesting plot idea could be that Naruto and Kishina travel back to a time when the Uchiha clan was still intact. They could try to prevent the future tragedies that are related to the Uchiha. Another idea is that they go back to a time when the Hidden Leaf Village was first founded and get to experience the early days of the village's development. They might also have to deal with different power structures and rivalries that were present at that time.
One idea could be that Naruto and Kishina travel back to the time when the Uchiha clan was at its peak. They could try to prevent the future tragedies related to the Uchiha. Another could be them going back to the era of the First Hokage and learning about the origins of Konoha and how it was built. They might also discover secrets about their own clans that were lost over time.
Maybe it's out of guilt. In the original story, Danzo has done some shady things that might have affected Naruto indirectly. So in fanfiction, he could care about Naruto as a way to make amends.
In fanfiction, sometimes the writers have their own interpretations. They could see Naruto's character in a way where his goals and dreams, like becoming Hokage, are so all - consuming that he simply doesn't have the emotional space to care about Sakura. His attention is diverted to more important things in his mind, such as protecting the village and his friends in a more general sense rather than having a special care for Sakura.
Not really. Fanfiction might play around with Naruto's character a bit, but it's tough to say he doesn't care about anyone. Naruto has such deep relationships with Sasuke, Sakura, Kakashi, and so many others. These relationships are a big part of what makes Naruto an interesting character. Even if a fanfiction tries to deviate from the norm, the essence of Naruto is his ability to care and form connections, and completely discarding that would make the story seem out of character and unappealing to many readers.
Because Naruto has a huge and passionate fan base. The original story is full of interesting characters and complex relationships. Fanfiction allows fans to explore different scenarios, expand on the existing story, and give their favorite characters new adventures.