The Pontifical Commission on Birth Control was a CONSULTATIVE commission which was, officially speaking, a commission of the Vatican Curia, and topheavy with cardinals, bishops and priest-theologians.  Members of that commission produced not just one report, but three -- a majority report, a minority report, and a majority response to the minority report.  [All three reports were published at the time, and prior to the publication of Humanae Vitae, right here in the National Catholic Reporter!]  The commission chairmen, Alfredo Cardinal Ottaviani, lobbied long and hard for the acceptance of the minority position (no change in church teaching), which is essentially what happened.  Thus, Humanae Vitae on birth control reproduces a clerical/minority report, which wreaked more havoc and did more damage to the Catholic church's credibility than the simple passage of time alleged here.  Of course Montini could have rejected Ottaviani's intervention, but that's another story, for another day.