I don't actually come from a traditionalist RC background, but in modern Catholicism, where I did come from, there is a lot of the Protestant spirit, namely the sense that it is now all right to question traditional dogmas and to revise them if necessary in order to conform to current ways of thinking. At first this drew me to traditional Catholicism (e.g. Latin Mass movement, not SSPX or sedevacantism!), but I realized that the RC Church had made the truth of their dogmas dependent on a single man, the Pope, so that if the Pope himself obviously deviates from previous teachings (as he has done in the context of ecumenism, for example), there is no way within the RC doctrinal framework to accommodate this. In Orthodoxy, on the other hand, the responsibility for preserving dogma lies with the whole people of the Church, as the Patriarchs showed in their 1848 epistle. Of course, it is theoretically possible that all the people could abandon the truth, but I suppose when that happens the world will end.
Anyway, even though pre-Vatican II Catholicism was much more (though not completely by any means) faithful to ancient Christian dogma, the seeds for the current disaster were already there.