If you are referring to yesterday's update to the procedures involving annulments, that was an update to Canon Law. Canon Law has a long and complicated history--most of which I am unqualified to speak about. However, there is a clear demarcation point in 1917 with the Code of Canon Law promulgated by Benedict XV. This Jus Codicis (law of the code) or Jus Novum (new law) compiled previous documents into one single volume and updated some practices. This book did not stay entirely static throughout its life, as multiple popes in succession added updates to the 1917 code up until 1983 when John Paul II promulgated a new Code of Canon Law. All of these apply to the Latin Rite, the Eastern Rite has a separate Code of Canons of the Eastern Churches (hence the need for two documents yesterday, one to update the Latin and another to update the Eastern). Yesterday's updates are headline-grabbing, but are honestly not all that shocking or unusual in my opinion.

As for the overall question about the papacy being a force for reaction or reform, there has been a lot of ink spilled over that subject. For Pius XII alone (the main focus of my research) there are more than a dozen books with various opinions on the subject. In some ways he was quite traditional and conservative, but in others he was a pioneer. For instance, he always had great reverence for the office of the papacy and was happy to use its grandeur to good effect. On the other hand his papacy saw one of the most rapid expansions of the Cardinalate outside of Europe in history. These two trends contrast a concentration of power in the hands of the papacy with a devolution of influence away from Catholicism's traditional power base (Europe, and Rome in particular). Pius XII was quite firm in keeping doctrinal authority in the Vatican, but was also open to new forms of scholarship and theological investigations (reference Humani Generis). I think most historians paint him as a traditionalist or reactionary to some extent, but I think that portrayal misses the complexity of Pius XII's attempts to engage with the circumstances of his pontificate (1939-1958). I think the most accurate portrait comes from Robert Ventresca's biography, but that's just one historian's opinion. I don't know if I could give you a definitive answer on this issue (reaction or reform) for Pius XII, much less the papacy in general.

I'm sorry if that's not a satisfying answer, but followup questions are always encouraged.