I looked to see if there were any later questions on living in the "horse-and-buggy days" versus the present. There didn't seem to be, but there were a couple that offered a choice between the past, present, and future. A 1964 question from a survey on Hopes and Fears of the American People (which I believe was part of an international survey):
"Here's a somewhat philosophical question. In general, are you completely satisfied to be living now in the present--or would you prefer to have lived sometime in the past, or to live sometime in the future? "
80% said they were satisfied with the present, 10% preferred the past, and 8% preferred the future.
In 1978, a Roper poll asked:
"If you could choose any time in history or any time in the future in which to live, what do you think your choice would be--to have lived at some time in the past, or to live at some time in the future, or to live in present day times? "
Now it was 60% for the present, 25% for the past, and 12% for the future. The questions aren't exactly the same, but I don't think that the difference is just the result of question wording. Having experienced the 1970s, I can see why many people would have been inclined to think that other times looked good by comparison.