The answer is here: The Federation of Diocesan Liturgical Commissions is really unhappy about the idea of revising Music in Catholic Worship.
"It is a matter of immediate concern to the delegates of the 2006 FDLC National Meeting: to reaffirm the importance of the BCL documents, Music in Catholic Worship and Liturgical Music Today, to support the BCL Sub-Committee on Music and Liturgy in retaining the basic principles of these documents in any revisions."