All of that happened back when the Church was supposedly trapped in the ghetto. Those numbers are the product of a time when the Church supposedly only communicated with the world to the extent hurling thunderous anathemas from on high required. All of that happened when the Church didn't practice ecumenism, or interreligious dialogue, when it upheld the social teachings of Christ the King, when the Mass was in Latin and supposedly no one understood it, when priests and bishops could be expected to manfully preach the solid teachings of the Church without needing constant goading from Rome, when the pope was still largely a "prisoner of the Vatican," etc.While all these numbers may make one yearn for the Church of old, a few of them are truly staggering for the modern mind to comprehend in today's Catholic-lite world: a 200+% increase in American converts; a nearly 250% increase in seminaries built; a 200+% increase in seminarians; and a 50% increase in priests. All of this happened over Pius XII's glorious 19-year-reign.
That's not to say there were no problems in the Church back then, but hasn't it always been so? By every quantifiable measure the Church was doing splendidly. She obviously went into free fall after Vatican II closed in 1965. Correlation does not prove causation but it does wave its arms and yell "Hey, look over here!" Counter-factuals are tricky, but it's foolish to think that Vatican II had absolutely nothing to do with the Church's utter collapse in the West.
It'd be one thing if progressive Catholicism inspired countless vocations and motivated the laity to kick ass and take names for Christ. Everyone knows that it doesn't. It's a narrow vision that appeals mostly to comfortable left-of-center folks with solid portfolios and nice neighborhoods. Instead of inspiring vocations to the priesthood or religious life, it inspires the clericalization of a select few lay people who take all the right classes, earn all the right certificates, and learn the secret handshakes in order to do "ministry:" parish administration, offering workshops to the next generation of chancery and parish employees, and the occasional communion service.
It wasn't so much the Church's structures and liturgies that needed change as it was ourselves. That was true then and it's true today. Vatican II was largely about tactics. Anyone with eyes in his head can see that the tactics embraced for the last fifty years have been less than successful. Since tactics don't necessarily touch on dogma, is it not possible to have a constructive dialogue (there's that word again) about when the old and tried are to be preferred over the new and untried?
The collapse of the Church was partly the result of changes in the culture at large. But sooner or later, we ourselves have to take responsibility for her collapse. Yes, bishops and priests are our leaders but poor leadership is not an excuse for us to become complacent in our mediocrity. In the age of the internet, you have no excuse not to learn more about the faith. In the end, we're going to be judged on our own lives, not on the poor decisions and example of our leaders.