Do you know why they used that series for so many of us?
No idea. Maybe because they were very innocent in nature and didn't praise the virtues of the "system"?
Perhaps, though I think it was also one of the more popular ones at the time in Europe. Innocent was good - at least better than un-innocent kinds like "Heaven's Girl." I would also like to point out that Peter and Jane did spend money, buy candy, go everywhere by themselves including an old castle on an island. I remember my mom just not making a big deal about those things. I do remember some adults saying that we don't eat candy and stuff like that. Though I would say they were pretty neutral in that they weren't evil neither were they saintly and portrayed an average middle class life style that most people from that generation would want. I don't mean the hippies.
I guess the wikipedia entry says it better:
"The books were first published in 1964, with a firmly 1950s feel to the illustrations provided by the furniture and clothing depicted, and the social context reflecting the life of a white, middle-class family. The books were revised and updated in 1970, and again in the late 1970s, to reflect changes in fashions and in societal attitudes."