from a gameplay point of view, I think that guns should not be added until/if there are a lot more hostile mobs that are dificult to subdue without them. otherwise guns are either too op or a letdown.
as far as gun ingame morally, eh idk. depends on how it is protrayed I guess. if its all about power and violence maddness, nah lets not. but If its about having more weapons in the game to play with, I think its ok in context