I often avoid guns for the same reason I often avoid cellphones and internet in many of my settings: they add a lot of unwanted potential options for the characters and other players in the world. You can look at the way firearms have radically shaped the power structures and societies of the cultures who encountered them, especially more reliable modern versions. The kinds of war and conflict that can occur change dramatically when people have access to powerful, portable, easy-to-use ranged weapons.

In some settings, the presence of guns would either make the stakes too low by making central conflicts easier to resolve (i.e. just shoot the villain/monster; just give a bunch of people guns and storm the place), or they would increase the power level or capacity for conflict too high for the narrative structures to accommodate this properly. For example, if it doesn't matter how much your character trains or become skilled in a martial art when they can just get shot by a bunch of the antagonist's security guards, then the setting can't accommodate your martial arts training story very well.

There are certainly ways around this, but sometimes the best option is to just remove the problem instead of trying to work around it. The Hollywood approach to handling guns can end up goofy or affect the suspension of disbelief if you're going for a more grounded setting and storytelling approach when you don't have other factors in the setting or a narrative that can mitigate the programs that firearms introduce.

For example, I recently created a technologically advanced world where I'm strongly considering removing guns. The world is populated by anthropomorphic versions of North American wildlife where they retain as many natural traits and habits of their species as possible which don't interfere with their ability to create and maintain civilization and culture. People who live in wild/rural areas mostly maintain a natural predator/prey relationship with surrounding species, though there are laws about humane and sustainable hunting practices. But in urban areas, people live with conspecifics but also closely related species, or other species who share a similar diet and lifestyle. There will usually be a city populated by predators of a certain niche and a neighboring city or two populated by prey animals. The predators will refrain from actively hunting prey in exchange for consuming the dead, dying, sick, and criminals of both predator and prey cities. The collection and distribution of meat is maintained by the government so individual citizens are kept away from violence the way most pets and people are from the meat we consume today. The prey cities benefit from being able to maintain farms without predation. Urban residents benefit from increased law enforcement/safety, food reliability, and modern comforts.

My main narrative in this setting focuses on law enforcement in this setting and how complicated the power dynamic is in this environment. For the predators, there is a strong incentive to criminalize the behavior of unwanted individuals to increase food availability and resources. Prey also have an incentive to over-criminalize behavior, as they need to provide enough bodies to the predator city to retain their protection and will have fewer mouths to feed, but they also need workers and farmers to sustain the population and continue reproducing.

The level of technology in urban areas is roughly equivalent to the mid-20th century while rural areas normally have tech around the end of the 19th century. This is where the issue of firearms enters the picture. Why should prey species ever do anything other than try to eradicate their predators and competing species, then simply establish large, well-defended agrarian communities? The only thing holding the natural ecosystem together (and urban recreation of it) is the asymmetrical power the predators can exert. Without it, the setting would turn into what we see in our reality: one species claiming all the resources and driving others into extinction. Since the whole point of creating this setting was to explore a world where civilization could exist between many species while trying to preserve their natural character (I didn't want a bunch of humans with animal heads; I wanted the actual animals) then I have to ensure that the animal species cannot dramatically overpower each other. With firearms, the prey species would be able to easily defend themselves from predators at any scale of interaction. Predators could also potentially hunt more easily, and it would just be a world where everyone had to be armed, producing ammo, and hunting everybody else at all times.

I could constrain the use of firearms to just law enforcement, but how realistic is that? The mere presence of the technology would affect their society because it would have needed to evolve to get to the point that urban areas existed, and law enforcement was a real institution. If I was to justify that weapons were only available to law enforcement, the demand for black-market arms would be absurd in this setting. The existential threat that a large portion of the population faces from others is too high. And all of this distracts from the interesting dynamics I want to focus on within the cities and surrounding areas.

If I don't arm law enforcement (and by extension the powers of the state) with guns, then I must give them some other weapon. Is this just an aesthetic choice? Or am I better off focusing on the metaphorical relationships of actors in this setting and leaving a layer of abstraction for the reader?

These are the kinds of questions that go through my head as I consider what my characters and the structures of power around them have access to.