Conevntional Wisdom (that is to say, the slander of Protestants and secularists) is that Vatican I was an incredible power grab of the papacy. The reverse is actually true: By delimiting the infallibility of the pope, all other matters of the church became open to ecclesiastical introspection. Which is not to say that all ecclesiastical introspection is valid, or that any challenges to theology which has not been doctrinally asserted is valid; it is a grave heresy, inconsistent with the magisterium, that any matter not infallibly resolved is questionable. Quite the opposite: Vatican I affirmed that deference must be made to tradition. One can deny with intellectual honesty theology which has not been ruled infallible, but which represents the current theological consensus any more reasonably than one can doubt any other science which represents the current scientific consensus.
To delve really deep into history and you’ll realize Martin Luther was not only right but only halfway through the tangled webs of deceit and confusion spun by the church he loved. To follow the Word of God or to follow church “tradition” is a choice we all have to make. They lead to different destinations.