The church of Rome has reversed its position on a number of very significant issues. These include salvation outside the church, capital punishment, and biblical inerrancy. Here's another example:
In earlier times a person who committed suicide would often be denied funeral rites and even burial in a Church cemetery.
Canon law no longer specifically mentions suicide as an impediment to funeral rites or religious sepulture.
In most cases, however, the progress made in the study of the underlying causes of self-destruction shows that the vast majority are consequences of an accumulation of psychological factors that impede making a free and deliberative act of the will.
Thus the general tendency is to see this extreme gesture as almost always resulting from the effects of an imbalanced mental state and, as a consequence, it is no longer forbidden to hold a funeral rite for a person who has committed this gesture although each case must still be studied on its merits.
How can you trust a denomination to be a safe spiritual guide when it reverses itself on such fundamental issues? If it changes it's position, then that means either of two things: if it got it right now, it got it wrong then; if it got it right then, it got it wrong now.
Also, why has Rome changed its policy? People commit suicide for the same reasons they always committed suicide. It's not like we've discovered new evidence.
Why are so many Catholic oblivious to how this renders their denomination unreliable? Several reasons suggest themselves:
i) Ignorance. For younger Catholics and converts, the new policy may be the only policy they ever knew. We know the present better than the past. We experience the present, whereas we must study the past.
ii) We're not inclined to criticize a change if we think it's a change for the better. If that's an improvement, then we think the change is a good thing.
But that misses the point. What does that tell you about the lack of institutional foresight?
iii) And, of course, you have a lot of Catholics who just don't think.
iv) There's always the out of saying Rome never addressed the issue authoritatively. For instance, Limbo for unbaptized infants was never dogma. Yet, for centuries, Rome left Catholics to believe that was the fate of unbaptized infants. Even if that's not a formal error, it is misleading the faithful. Misdirecting them rather than guiding them into the truth.