Let me try to answer this difficult question:
The Catholic Church has a right to regulate her official liturgy and prayers (except, of course, certain parts of the Mass and sacraments that are fixed by Our Lord Himself).
That being said, a horrible liturgy resulted from the work of the Vatican II implementation committee. Their creation, the Novus Ordo Mass (NOM), has very few things specifically Catholic in it, while it contains a plethora of Protestant elements (from Cranmer's liturgy, Luther, etc.)
The NOM, whether or not it is valid, has certainly resulted in a loss of Faith in both priests and laity, as evidenced by the general apostasy of the last 36 years (declining vocations and Mass attendance, ignorance and loose morals among the Faithful, heretical beliefs among priests/laity, etc.) Some people in 1970 might have questioned such a criticism of the NOM, ("Hey, give it a chance!") but with 36 years of "fruits", we can now reliably judge this "tree".
Is the NOM valid or not? Does it matter? Even if valid, it is not safe for Catholic consumption. It tends to weaken/destroy the faith of Catholics who attend it. Even if someone attended the NOM because of lack of traditional "options", it would still require a constant judging -- by a layman -- of his priest, which is not an acceptable proposition.
Saying the NOM is not valid, however, creates more problems than it solves. First of all, it says the Crisis in the Church is much worse than we already know to be true. Next, it means that countless devout Catholics, even those with the Faith, are not attending Mass or receiving Jesus in Holy Communion. Would Our Lord permit the gates of Hell to prevail over His Church? Because if the NOM is not valid in any case, then Our Lord has effectively abandoned Catholics of good will who have not yet found the Traditional movement.
And since everyone who says the NOM is invalid ALSO says that the new Rite of Ordination is invalid, it also means that there are only a few hundred (maybe a thousand?) valid priests left on the earth.
A Catholic of good will (and who still has the Faith, by the preserving grace of God) would not be party to the more abuse-intensive Masses, nor would they seek out the more liberal priests. All the ugly abuses (such as those featured on a certain website) would turn off most Catholics who still have the Faith. They would likely go "parish-shopping", though they would stick to N.O. parishes.
As we speak, there are many good Catholics who still attend the NOM. They are trusting their priest that the SSPX is in schism, that they have to obey the Pope, etc. Even though they are mistaken, they are trying to do God's will. If they could be made to understand Modernism, 50's Catholicism, the Liturgical movement, the history of the Church, Vatican II, etc. they would probably end up at a Traditional Mass center, approved by Rome or not.
One important point is the fact that not all N.O. Masses are the same. There are some that are done according to the rubrics, with all possible reverence. At the other end of the scale you have clown "masses". But usually you have something in between, which varies by diocese, parish, and even by priest.
I know that some traditional Catholics are so horrified at the thought of Hosts being left on the floor, etc. that they can't fathom that Our Lord would tolerate such abuse of His Body. Indeed, it is a great horror. Everything that is Catholic in me is repulsed by it. But abuse of Our Lord in the Blessed Sacrament is nothing new. It has happened since the beginning, though perhaps not on so large a scale. Perhaps most of the "Masses" where such abuses take place are lacking some element necessary to validity. But that doesn't mean that the N.O. rite, as promulgated by Rome, is in all cases invalid.