Here's the thing. Nobody was listening to the Church. The modern world had completely high-jacked faith for most people. This wasn't the fault of Vatican II, it was the reason Vatican II was called. Enlightenment philosophy had drastically shaken the modern understanding of authority and the nature of obedience to Church teaching was being questioned (and under heavy fire). Remember, the bishops were products of the faith-crisis, and many of them held out a hope that the Church's teachings could actually change... according to certain perspectives and philosophies so pervasive during the decades preceding and following the Council, this was entirely plausible.
What people need to understand is that Vatican II is a part of the Tradition now and, like everything in the Tradition, it needs to be interpreted by the living Magisterium of the Church. Why did so many bishops misinterpret the Council? Why did so many Bishops allow misinterpretation? Because they were formed in the world that needed the Council. Like most people, they weren't listening to the living Magisterium. The voice of the Church wasn't being heard, from simple peasants all the way into the ranks of Cardinals. That is the crisis Pope John XXIII (and others) recognized and so the reason for the Council.
For me, it's all the more affirming that the Holy Spirit truly does guide the Church and, here especially, the Councils. It was a trying moment in the life of the Church. The questions abounded. Even the best men were caught in the confusion. What was the answer? How should the Church react to the modern crisis? What can change, and what cannot change? These were difficult questions, and what might look like failure and foolishness in hindsight is simply the human side of the experience. Furthermore, the event of Vatican II itself was in-part made up of many men who had lost touch with the heart of Catholic thought and practice (products of the culture), and yet the Lord still moved the Council Fathers to lay the foundation for what would eventually reach these same men. Does that make sense to you? I find it fascinating!