The most frequently heard complaint of our Liturgical praying is that it is repetitive. They must come from a heart desiring to seek God Himself. These liturgical acts then, do not violate Jesus' command against vain repetition. Two last points. St. Paul insists that harmony with God, ourselves and other people is made possible through Christ who unites human beings to God and each other.
Peace is the underlying condition of all prayer.
So the people's 'shorts' are not just an expression of assent, but are an outward and audible sign that we are interiorly pray-ing along with the said prayers. The answer is easy. Our way may be hard and long. And, just as the action of the Holy Spirit changes the Bread and Wine into the Body and Blood of Our Lord, so the operation of the same Holy Spirit is, over a lifetime, changing us into whatever God wants us to be i.e. people blessed in the Kingdom of the Father and the Son and the Holy Spirit, now and unto the ages of ages. The Services of Holy Week are many and a rich source of salvation in our lives through the power and operation of the Holy Spirit.