Donatist revival inadvertently fostered?

I was recently listening to a presentation recorded some years ago by the late Anne Roche Muggeridge, the daughter-in-law of the famed journalist and author, Malcolm Muggeridge.
The author of reflective and insightful books, like Gates of Hell (1975) and The Desolate City: Revolution in the Catholic Church(1990), Anne Roche Muggeridge was a champion of traditional Catholicism who stalwartly resisted the anarchism of the post-Vatican II decades. She died in Toronto last year on my birthday, the Feast of the Exaltation of the Cross (September 14, 2010).

In her presentation she made the startling observation that the liturgical chaos following the Council had foisted upon faithful Catholics the onus of having to determine for themselves whether a given Novus Ordo Mass was valid or not by assessing how the priest celebrated Mass, whether he departed from the text of the Missal or stuck to the rubrics, etc. -- and that this, in turn, had inadvertently revived the Donatist heresy of constantly focusing on the personal disposition of a cleric to determine the validity of a Sacrament.

St. Augustine's reply to Donatism, of course, was that the Sacraments are valid "ex opere operato" -- i.e., that the validity of a Sacrament depends not on the worthiness or holiness of the minister performing it, but upon the worthiness and holiness of God who is the principal agent in dispensing sacramental grace. The hitch, however, is that the efficacy of ex opere operato hinges in some indispensable ways upon the person of the priest, such as his providing valid matter, speaking the words of the formula correctly and with the intent of causing the Sacrament to occur validly in keeping with the mind of the Church, etc. And this is the arena in which doubts sometimes raise their heads.

It's an interesting point, and recalls the lamentations of Martin Mosebach in Heresy of Formlessness (Ignatius, 2006) about simple Catholics being obliged these days to become liturgical experts simply by dint of the constant innovations they must assess. It is a huge burden to foist upon ordinary Catholics -- those euphemistically called "pew peasants" -- to require them to cultivate a discerning nose for discerning the difference between liturgical chicken soup and liturgical chicken ... well ... perhaps you see the point.

Why couldn't Catholics simply stick with the dance steps received from the past -- with perhaps a minor adjustment of a given move here or there (at most!) -- and concentrate their minds on their Divine Dance Partner, rather than be treated to a barrage of constant changes in the dance steps themselves, which has forced them to focus on their own feet instead? Even St. Thomas Aquinas makes the point in his Treatise on Law that changes of any kind ought not to be introduced into law (in this case, liturgical law) unless the net positives far outweigh the net negatives, for the effect of any change itself is to some degree to undermine the received (liturgical) law.

Anne Roche Muggeridge jokingly lamented that circumstances in the Catholic world were turning her into a Donatist. How unutterably sad!