I think I know the answer to that. Again, from http://www.jashow.org/Articles/apologetics/AP0704W2.htm:
Theologian Dr. Bernard Ramm observes that, "The story as to how the Apocrypha achieved [the] status of inspired Scripture at the Council of Trent is one of the saddest commentaries on improper scholarship in the history of Western culture."5
Biblical scholar R. Laird Harris observes that for 1,500 years no Roman Catholic was called upon to believe the Apocrypha was scriptural—until the Council of Trent made its fateful decree. He agrees the Council adopted its position "for reasons of expediency rather than evidence."6 Thus, the Council was "unmindful of evidence, of former popes and scholars, of the Fathers of the church and the witness of Christ and the apostles" in making its pronouncement.7
Dr. Rene Pache points out that a key reason for Trent’s decision was to respond to the arguments of the Protestant Reformers who were attempting to defend the principle of sola scriptura—that the Bible alone was the final authority for matters of faith and practice, not church tradition. Thus, Trent found in the Apocrypha a justification for unbiblical Catholic traditions that were rejected by the Reformers.
Why, then, did Rome take so new and daring a position? Because, confronted by the Reformers, she lacked arguments to justify her unscriptural deviations. She declared that the Apocryphal books supported such doctrines as prayers for the dead (II Macc. 12:44); the expiatory sacrifice (eventually to become the Mass, II Macc. 12:39-46); alms giving with expiatory value, also leading to deliverance from death (Tobit 12:9; 4:10); invocation and intercession of the saints (II Macc. 15:14; Bar. 3:4); the worship of angels (Tobit 12:12); purgatory; and the redemption of souls after death (II Macc. 12:42, 46).8
Thus, a strong case can be made that the reason the Council of Trent declared the Apocrypha canonical was simply as a polemical maneuver to support Roman Catholic belief against the Protestant Reformation. To illustrate, two main doctrines in dispute during the Reformation, both supported by the Apocrypha, include salvation by faith/works (Tobit 12:9) and prayers for the dead (2 Macc. 12:45-46). Concerning these doctrines, the Catholic Church claims that they are scriptural because they are canonical (i.e., apocryphal). For example, concerning prayers for the dead in 2 Maccabees 12:39-36, we find the practice of postmortem intercession where the living are able to make "propitiation for the dead,"9 allegedly loosing them from the consequences of their sins and thus undergirding the Catholic doctrine of indulgences and prayers for the dead in purgatory:
…the troops of Judas went… to pick up the corpses of the slain… they discovered under the shirts of every one of the dead men amulets of the idols of Jamnia—a practice forbidden the Jews by law. All saw at once that this was why they had perished [by the Lord’s judgment] and… all betook themselves to supplication, beseeching that the sin committed might be wholly blotted out… [Judah] collected from them, man by man, the sum of two thousand drachmas of silver, which he forwarded to Jerusalem for a sin-offering. In this he acted quite rightly and properly…. Hence he made propitiation for the dead that they might be released from their sin.10
Notice however that these verses 1) do not even mention purgatory and 2) actually reject the Catholic doctrine of purgatory by teaching that deliverance of soldiers who had died in the mortal, and hence unforgivable, sin of idolatry. Regardless,
The acceptance of the Apocrypha at the Council of Trent is suspect because: ...it was used against Luther in support of the Roman Catholic position…. [Further] Not all of the Apocrypha was accepted. Only 11 of the 14 books were and one of those admitted books (2 Esdras) is against prayers for the dead….11
We emphasize once again! Material that is either contradictory, legendary or heretical can hardly be accorded canonical status. The canonical books clearly oppose salvation by works (Galatians chs. 2 & 3) and praying for the dead (Hebrews 9:27; 2 Samuel 12:19; Luke 16:25-26). Stories such as those found in "Bel and the Dragon" are clearly legendary and therefore unauthentic as are the "Additions to Esther," "Prayer of Azriah," "Tobit," "Susanna and Judith." At other places the teaching of the Apocrypha is even immoral, e.g., where Judith was allegedly assisted by God in an immoral action (Judith 9:10-13). Both "Wisdom" and "Ecclesiasticus" teach morality based on expedience. Again, there are numerous errors in the Apocrypha. William H. Green concisely observes: "The books of ‘Tobit’ and ‘Judith’ abound in geographical, chronological, and historical mistakes, so as not only to vitiate the truth of the narratives they contain, but to make it doubtful whether they even rest upon a basis of fact."12 This probably explains why "Many of the great Fathers of the early church spoke out against the Apocrypha, for example, Origen, Cyril of Jerusalem, and Athanasius."13
It’s not difficult to see how the beliefs changed over time to accommodate the power Rome was trying to hold on too. Contrary to what they would like us to believe the RCC has surely not been consistent through the years.