Did the Church Change the Mass So it Would be More Acceptable to Protestants?

The Church’s primary concern in the reform of the liturgy was not the sensitivities of Protestants but the active participation of Catholic laity:

This sacred council [Vatican II] has several aims in view: it desires to impart an ever increasing vigor to the Christian life of the faithful; to adapt more suitably to the needs of our own times those institutions which are subject to change; to foster whatever can promote union among all who believe in Christ; to strengthen whatever can help to call the whole of mankind into the household of the Church. The council therefore sees particularly cogent reasons for undertaking the reform and promotion of the liturgy. (Sacrosanctum Concilium 1)

Although the Second Vatican Council does include a concern for reunion among Christians within its reasons for liturgical reform, it does not give that as its first reason for the reform. Even so, the unity of Christians is a valid concern for the Council to have considered given the importance Jesus himself places upon it (John 17).