The use of "nursery" is interesting and ironic since it is the most dangerous room in the house, and anything but a nursery as the children are not babies, and their games are anything but harmless children's activities.
Also ironically interesting is the use of the names Peter and Wendy, which are suggestive of the fantasy novel Peter Pan, or The Boy Who Wouldn't Grow Up. This is a charming children's story about a boy who refuses to mature into a man, and wants Wendy to remain a child with him. However, Wendy is allowed to return home when she tells Peter that her place is at home.
But, what is interesting about the nursery, too, is that rather than being a soothing bedroom, it is the room in which Mr. and Mrs. Hadley are destroyed as the children's room has evolved into much more than intended. For, the virtual reality has overtaken the true reality, and the children become confused in their use of the technology, believing that their anger against their parents is justified because the room, the nursery, encourages the children in their sadistic desires. Thus, the technology produces the reverse effect from what has been intended. Rather than provide the children an outlet for their energy or negativity, the Veldt becomes a sinister room.