In most well known fantasy thrillers, many writers choose to add an extra spice to their stories. This spice is violence; battles filled with bloodshed, characters getting their bodies mutilated by scary monsters, and horrific injuries to just name a few of this trope's most prevalent elements. Fantasy novels, especially those targeted at a tween and teenage audience, usually have some form of violence in their stories. Many writers include the blood shed for the reason of shock value to the audience. This in theory creates an overwhelming obsession to find out if the characters will make out of whatever violent conflict they have gotten themselves sucked into. The audience's obsession with the situation presented is what these writers believe will be a factor in continuing to read their material. Authors with this mindset will make the most crazy, bloody stories possible, not realizing that by focusing on the shock value alone the story suffers. They do not see the reasons why the authors who influenced them added such scenes into their own works. Their acts of violence were not to merely give the audience a sudden shocking thrill. These authors added the scenes in to truly add more meaning into the messages they were trying to preach.
Take for example Animal Farm's notorious scene of Boxer being fooled into his death by glue factory thanks to the dictatorship of Napoleon the pig. Author George Orwell did not add this scene into his classic novel to just merely shock or engage the audience. Instead, it was to drive home the point that Napoleon had become so twisted from his leadership that even those most loyal to him were disposable. Boxer time and time again proved to be one of the hardest working animals in the entire farm. When the windmill was destroyed by Mr. Frederick after the animals had worked a whole year to build it, Boxer was the first one to step in for its repair. He did the same when gathering wheat from the fields, fighting to defend the freedom given to the entire farm, and when trying to memorize the human alphabet. This character was a source of motivational hope for the animals. With his untimely demise at the hands of Napoleon, it reinforces George Orwell's overall message of the book; communism, a warped form of the idealistic socialism, is a danger to society. No one can be safe from its unforgiving talons. Boxer's gruesome death was an example of a strong writer wanting to spread an important message not really well known to the public at the time. It was not for cheap thrills, unlike other "edgy" stories.
There is also the manga version of Tokyo Ghoul, which is known to be over-the-top crazy with its depictions of violence. At first glance, you may believe the writer Sui Ishida wanted to add the violence as a spice for the serious and sometimes even insane aura crafted into his story. Like with Orwell, Ishida did not add the crazy amounts of violence just because he could. Instead, the blood stained fights are symbolism for the external struggle between the human race and the ghouls. Humans believe that all ghouls are out to get them like a plague. In their minds, the only way to bring peace to Japan is to exterminate them one by one. Ghouls meanwhile are in one of two classes in the conflict. In the first one, ghouls see humans as merely food that helps to sustain their insanity causing hunger, as an enzyme in their bodies prevents them from eating anything normal other than coffee beans. In the second one, ghouls want to co-exist with humans and use their need to feed for cleaning the streets up of dangerous criminals. They are judged though before this ideology can be expressed and must hide in the shadows to prevent being killed. For Ishida, the violence is merely symbolic. It was not done for the thrills you might find in some of the more recent Michael Bay Transformers films.
Nothing is done without reason. These scenes are no different. Violence to these authors does not come before cause. Expecting the audience to get engaged from random scenes of gore is both nonsensical and debatably inhumane. The story's meaning floats above these small violent trope spices. Causation is not without representation, a statement that could not be more true about violence in literature.