Not everyone at VII wanted it changed…
“In recent times, even in materialist North America, the growth of the Church was magnificent with the liturgy being kept in Latin. The attempts of the Protestants have failed, and Protestantism uses the vernacular. We ask again: Why the change, especially since changes in this matter involve many difficulties and great dangers? All of us here at the Council can recall the fundamental changes in the meaning of words in common use. Thus it follows that if the Sacred Liturgy were in the vernacular, the immutability of doctrine would be endangered.
The introduction of the vernacular should be separated from the action of the Mass. The Mass must remain as it is. Grave changes in the liturgy introduce grave changes in dogmata.”
-James Cardinal McIntyre addressing the Second Vatican Council.