How horrible to say such a thing. Nor did you accurately represent Hermann who said "Mozart masses are not an end but a means." He meant that a certain level of aesthetic appreciation is not a requirement. Even there I disagree with him, but only slightly.
But the Mass is the end of all ends. It is the perfect worship of God which is the purpose of all creation. Why does the universe exist, rather than a condition of non-existence? To give praise, honor, glory and worship to God. This is why the stars, the planets, and ourselves were created and exist. What is the most perfect possible way to accomplish that purpose? Through the Mass in which Christ's passion and death on the cross is reenacted. When properly offered, the Mass exceeds even the worship offered to God by the angels in heaven. There is no purpose beyond this.