Cal writes:

<<
i took the first class of the new math in pasadena in 1960 (7th grade) - my
class had an advantage over most of the other people i know who encountered it
then or later; my teacher didn't know anything about it, just like everyone
else's, but it DIDN'T bother him ...
>>

I believe Cal is exactly right.  The main reason for the downfall of the New Math in that era was that a large number of teachers felt they were being asked to teach something they had never been taught.  Since math has always had a problem of being taught, esp. in public school, by too many teachers who are already  prejudiced against it, this new externally-imposed curriculum just exacerbated their negative feelings.

--Dan