Why did John XXIII convene a commission to study contraception if the teaching was not in question? And, why did it take Paul VI TWO YEARS to respond to the leak that the commission had recommended that the teaching BE changed?
The silence let the the horse out of the barn, so to speak.
As you well know, the teaching itself was NEVER under question. What was studied was the effects of the drugs and whether such effects were in conflict with the teaching. This was done largely because some powerful American interests (Rockefeller & Co, J&J) had persuaded a number of high-ranking clerics that perhaps 'the Pill' was not in conflict with constant Church teachings
And, why did it take Paul VI TWO YEARS to respond to the leak that the commission had recommended that the teaching BE changed?
Regardless of the Commission's recommendation, Paul VI studied the matter again and consulted with other individuals. As you know, the leak was from an American couple who were later VERY active with Call to Action. They were then, and remain to this day, dissidents, like UpChuck Curran.
The silence let the the horse out of the barn, so to speak
Only someone with a serious "moral-education-deficiency-syndrome" combined with a serious "inclined-to-disobedience-anyway" syndrome would act AGAINST existing Church teaching in anticipation of a change which was at best, a 50/50 proposition.
Of course, the dissidents (many priests and Bishops), did their best--I don't necessarily blame the laity, until AFTER the Pope wrote the encyclical.