I think the reaction against New Math was a part of the general reaction against all of what many viewed as the "weirdness" of the 60s, an anti-intellectual attitude that was often used by powers-that-be that also felt threatened by these upheavals.

My, I'd be happy if we had military dictatorship which imposed a new order including the metric system, radians instead of degrees and algebra from 1st grade onward. But I don't think that program would have a sufficient constituency.