I think that zombies are meant to be used as horde types, and zombies shouldn't be smart enough to use the weapons.
You could modify this to be a moderator-only class, used to balance unfair gameplay tactics, or maybe as a side-quest type.
This. One of my least favorable zombie films is land of the dead. It is the zombie version of twilight to me; it simply ruins the idea of thoughtless zombies after that one goal to eat everyone alive. Using guns, and understanding how to explode cars? GTFO.
I personally hate the idea of a zombie that can kill from a distance. When using a ranged zombie in a mini-game of mine I chose to have a 'boomer' that threw a sock (and could not tag) and forced a human to stand still for 2 seconds, imparting them to fire their blaster as well.
I was killed by a ranged zombies sock tag(which stunned me so I couldn't run/shoot) and then devoured by a horde at one of my best games which left me baffled at first. In general, the idea of a sock or thrown only weapon seems fairest since the accuracy isn't purely range based, nor is it on always on par to some of the weakest blasters some use. It is a challenging encounter that only a specific fellow moderator at my home campus has the ability to do. In general, his strikes are lethal.
Give zeds ranged attacks, and suddenly you don't need to worry about smashing into the human tank; I'll just sit back and pot shot it, and because humans will be massed up, it'll be easier for me to hit them than for them to hit me. Give humans melee and you remove the need to distance yourself from the zombie menace (it's also OP as fuck). Sure, you can have a game of tag if you monkey with either of those tenants, but I don't view it as a "true" HvZ experience.
My home campus and another I've played at allow melee and as much as I wish it didn't, it is part of the recipe that makes up our game. I feel it changes alot of the core HVZ you speak of. I mean, whats to stop the 95% of the human pop. from making a 3$ melee weapon from PVC and pool noodle? But I digress...
Pot shotting the humans is a general tactic for most ranged zombies since the instinct all humans have is to either turn there backs and run(thus not dodging the shot/sock) or clumping together.