No, what progressives want is not "fuller meaning"
You do realize that those whom you refer to as 'progressives' are the Council Fathers. Furthermore, liturgical renewal did not begin with Vatican II.
While the reasons for changes in the Instruction Generalis of the Missale Romanum, editio typica tertia, are at one level part of an ongoing process of revision, it is a revision which is faithful to the theological vision and directives of the Council Fathers. If we approach from this theological vantage point, our implementation of this reform will be derived from a liturgical-theological reflection rather than rubrical adjustements or minor modifications. The Instruction Generalis is part of an ongoing process of liturgical renewal and represents an organic continuity with the theological vision of the Council Fathers.
The Instruction itself recalls that the Fathers of the Second Vatican Council were continuing the work begun by Pope Saint Pius V, who in the promulgation of the Roman Missal wrote that its goal was to give to the liturgy the vigor it had in the tradition of the Fathers. The succeeding Roman Pontiffs directed their energies during the subsequent centuries to ensure that the rites and liturgical books were brought up to date and when necessary clarified for example the outstanding work of Pope Benedict XIV.
The twentieth century opened with the establishment of a special Commission for a general reform of the liturgy by Pope Saint. Pius X.
The Liturgy has always undergone modifications throughout the centuries, there is only one unchangeable text and that is the text of sacred Scripture.
I sincerely hope that you take the time to read all of 'The Theological Vision of Sacrosanctum Conciliumand the Roman Missal'
The Theological Vision of Sacrosanctum Concilium and the Roman Missal