Some people might create 'Boruto' abused fanfictions out of a desire to explore dark or edgy themes that are not present in the original series. But this is a wrong approach as it goes against the positive nature of 'Boruto'.
It could be that a small number of writers want to shock the audience or get attention by creating such inappropriate content. However, the vast majority of the 'Boruto' fandom does not support this kind of fanfiction. The 'Boruto' series is about hope, growth, and the new generation of ninjas, and these dark fanfictions are a perversion of that concept. They might also be created by those who misinterpret the characters and want to take them in a very negative and untrue direction.
I'm not sure there are truly 'popular' ones that involve abuse as that's a very dark and inappropriate topic. Fanfiction should generally promote positive themes. However, if there are any, they are likely to be found in some of the more unregulated fanfiction websites, but I cannot recommend or promote such content.
One reason could be to explore the darker side of the character. Draco is often seen as a complex character in the Harry Potter series. By creating 'Draco is abused' fanfictions, authors can dig deeper into his possible traumas and how they might shape his actions and personality. It adds more depth to his character.
They are popular because fans love seeing the father - son relationship between Naruto and Boruto explored. Naruto is a beloved character, and seeing him show affection to his son in fanfictions is heart - warming.
These fanfictions are popular because Naruto is such an iconic character. Boruto's love for him represents a new generation looking up to the old hero. It gives fans a chance to write about the transfer of values and ideals from Naruto to Boruto, which is really appealing.
For drama. Writers often create conflict to make the story more interesting. Making Boruto hate his family in fanfiction is a way to introduce a big, shocking conflict.
Some exist to explore darker themes. Writers might want to show the resilience of a character like Frisk in the face of extreme adversity. For example, by having Frisk go through abuse, they can then show how Frisk overcomes it and grows as a character.
Well, it's mainly because it shows a different side of Snape. In the original series, Snape is often seen as a complex and somewhat antagonistic character towards Harry. In these fanfictions, his act of saving Harry gives him a chance at redemption. It also adds an interesting dynamic to their relationship, which was mostly strained in the books.
They're popular because it offers a different perspective on the Harry Potter universe. We get to see Snape in a more nurturing role which is quite different from his canon portrayal.
They are popular because many people can relate to the idea of finding hope and healing. The abused reader represents those who have been through tough times, and Team Minato is a symbol of support and new beginnings. People like to see how the characters in the fanfiction can overcome their past and build a better future.
One reason could be that it takes more time to create detailed and high-quality art for each chapter. The story might also be more complex, requiring more planning and refinement.