Educated Catholics of a certain stripe know why, for example, in vitro fertilization (IVF) is immoral. The teaching is summarized for all to see in the Catechism; the deeper theological explanation is given in a CDF document written principally by then-Cardinal Ratzinger about twenty years ago. But many Catholics accept IVF for infertile couples as a matter of course. Many of those do not even know the Church's teaching; some of the more educated among them do know it but reject it along with its rationale. It gets worse. The most recent poster children, as it were, for the new genetic-screening technique of "pre-natal diagnosis" (PND) are a nominally Catholic couple; yet according to Church teaching, PND is wrong for the same reasons that ESCR is wrong, and even more blatantly so. Most Catholics know little of that and care less. Yet there's no reason to believe that things would have turned out differently if the bishops had slammed the barn door shut sooner—say, twenty years ago.
Almost as soon as it was issued nearly forty years ago, amid the upheavals associated with Vatican II, the majority of Catholics rejected Pope Paul VI's encyclical Humanae Vitae reaffirming the ancient and irreformable teaching about contraception. Never having been taken to task for that, the laity continue to act accordingly even though HV's teaching is reiterated without compromise in the CCC. And once people accept the idea that procreation may be actively excluded from sexual intercourse, they start losing the ability to see why it's wrong to procreate without sexual intercourse. It's a matter of spiritual if not formal logic. Once Catholics get comfortable with the illusion that the constant and irreformable teaching of the Church can be ignored with spiritual impunity, things fall apart fast indeed.
Over the past generation, the divorce rate among Catholics has increased, and the marriage rate has declined, roughly in tandem with those rates in the general U.S. population. In fact, the majority of Catholics no more accept and live by the Church's developed theology of marriage than most non-Catholics. Yet for reasons that make practical sense, the bishops require that a civil divorce be completed before a nullity petition may be brought before a diocesan tribunal. That policy has had the unintended effect of reinforcing, even among many devout Catholics, the idea that divorce is just one of the many necessary evils that mature adults must learn to live with. Now that unilateral, so-called "no-fault" divorce is the norm, the idea in question causes many ostensibly Catholic marriages to be abandoned without sufficient reason even when one spouse is opposed to the idea, and leads the spouse initiating the divorce to expect vindication by the Church in due course and as a matter of course. I know by direct, firsthand experience as well as by observation that that expectation is usually justified. So, despite the best of intentions, the Church has become complicit in the divorce culture and thus in the disintegration of the family that, proceeding ever apace, heralds deep social decline.
I do not say these things to be critical of the bishops as individual men. I have great respect for Bishop Jugis and for a good number of other American bishops—especially that relative handful who, like Jugis, have put themselves on the line by directing their priests not to give the Eucharist to "pro-choice" Catholic politicians. But even the best bishops don't seem to grasp the significance of the fact that, for most American Catholics, the moral teaching of the Church is mostly just a matter of opinion—one that, as such, admits a variety of opinions. That attitude is pellucidly reflected in the response of some CINO Congresspersons to the Pope's recent claim that politicians who formally cooperate in abortion, by making and/or keeping abortion legal, are unworthy to receive the Eucharist. Those legislators were only reflecting the default stance of most American Catholics. Until that default stance is changed, anything the bishops say about political issues bearing great moral import will only be preaching to the converted. It will not have the educative effect they intend.
It's not much of a challenge to issue statements that are true and justified, such as the recent statements of the bishops about proposed ESCR legislation. The challenge is to get Catholics to understand that the moral tenets involved are not merely matters of opinion. The challenge, in other words, is to re-establish the moral authority of the Church. The sex-abuse scandal made that still more difficult in a society where it had already become difficult. The only solution is the example of conspicuous fidelity and holiness in the clergy, especially the higher clergy. How that is to come about, I cannot say. But unless and until it does, nothing the bishops say or do as a body will have much effect.