I think the biggest way in which Bradbury uses characterisation and narrative voice to present the social commentary of the story is through the presentation of the children and what we are told about them. Clearly, Bradbury is presenting us in this story with a futuristic world which has become so advanced that individuals are able to become more fixated on an unreal world than their real world. Note the children's obsession with the nursery and the illusions that it creates for them. Note what McClean says to George about the importance of the nursery for the children:
You've let this room and this house replace you and your wife in your children's affections. This room is their mother and father, far more important in their lives than their real parents.
Peter and Wendy are presented as being so dependent upon the Nursery that they are unable to cope with even the idea of being deprived from it. Note how Peter responds when he is told that the Nursery is to be closed:
"Don't let them do it!" wailed Peter at the ceiling, as if he was talking to the house, to the nursery. "Don't let Father kill everything." He turned to his father. "Oh, I hate you!"
McClean's observation about what the Hadley's have allowed to happen is thus justified through the way in which Peter turns against his own father. Thus it is that the characterisation of the children, and the way that the Nursery has become more important and real to them than reality and their parents, thus is used to present Bradbury's grim message about technology. We must ensure that we do not become so dependent on technology that we forget how to actually live without it.