When would random "civilians" use their guns though? They can't shoot the gangs, as that would just invite reprisal. That leaves random non-gang thugs.
If you get stopped on the street by a non-gang thug with a gun pointed at you, are you going to try to quick-draw on him or are you just going to give him your wallet? Would a random civilian in Night City pull a gun to help defend a random stranger being mugged? Knowing that the random stranger might have an older brother who runs with the local gang, going around being John Wayne seems a sure way to an early grave (unless you actually have the skills to back it up like V does).
I think the "run and hide" reaction is far more reasonable for all the randomly generated people on the streets the game is populating the city with. Perhaps there should be some non-gang "tough guys" sprinkled in there that would actually go into combat mode when appropriate, but for your average non-gang person in Night City, pulling a gun is the worst survival strategy.
Of course if you aim your gun into someone's face, they won't be able to do much unless psychos. We don't need to make every pedestrian aggro at the first sight of a gun, but we need more of these:
1) You pull someone out of a car and try to drive away - if the owner isn't neutralized (lethal or non-lethal way), he might open fire on you.
2) You damage someone's car or stand on the roof or whatever. Owner should get angry, get out of a car, aim his gun at you or even start shooting.
3) We need cowboys injected into the crowds. You start firefight on the streets or in a shop, they might join in.
4) Bump into someone not nice, they might aggro, including using guns.
5) Pull your gun nearby chilling guys, they might threaten your to holster it or you will get your ass kicked. If 20 years old Gothic can do that and it looks believable, why Cyberpunk can't?
From top of my head. And it's only regarding folks on streets. There are many more opportunities to make the city feel more dangerous.