I also thought MD 100 was a little foggy about the transition between preaching sin with the laity and the sanctification and cooperation of the clergy with the grace of Christ.
Pope Pius XII here suggests the externals of the liturgy also assist in the focus on the Divine, reminding his bishops of what was taught at Trent:
101. The prescriptions in fact of the sacred liturgy aim, by every means at their disposal, at helping the Church to bring about this most holy purpose in the most suitable manner possible. This is the object not only of readings, homilies and other sermons given by priests, as also the whole cycle of mysteries which are proposed for our commemoration in the course of the year, but it is also the purpose of vestments, of sacred rites and their external splendor. All these things aim at “enhancing the majesty of this great Sacrifice, and raising the minds of the faithful by means of these visible signs of religion and piety, to the contemplation of the sublime truths contained in this sacrifice.”[Cf. Council of Trent, Sess. 22, c. 5]
The challenge in some cultures, more so today than in the past, is that more people distrust the externals. They do not hold the same awe and wonder. And in the West, the spectacle of secular architecture, not to mention entertainments, can outdo (when they try) the beauty of the liturgy without very great cost.
While I’m not prepared to dismiss traditional liturgy out of hand, I sense many lay people are looking for something deeper, more moral, and steeped in sincerity.
Catholic Sensibility 