Including the books doesn't mean they were always cosidered to be inspired. And I find it interesting how you disregard the first centuries' take on them; usually catholics would count the early fathers' opinions as sacrosanct.
It's usually only the spur of dissent or the pressure of controversy that motivates the forensic "defining"
I don't know about "usually". But in this case it's the Biblical content itself as well as other external factors such as the Jews never having considered the apocrypha as inspired (for good reason).
It's good history...not inspired.
The Jewish leadership only rejected them based on the fact that they so strongly facilitated Christian beliefs such as eternal life, the resurrection of the dead, and the cosmopolitan (non-ethnic-Jewish) breadth of the Christian community.
Of course you're going to have to depend on some extra-Biblical authority to determine what the canon of inspired Scripture is, since the Bible itself did not come with a table of contents. The Christians had their councils (Hippo and Carthage) and the anti-Christians, led by Rabbi Johanan ben Zakkai, had theirs (Jamnia). The Christian councils kept the LXX and the deuterocanonicals; the rabbinical council at Jamnia, reacting against the spread of Christianity, threw them out.
Just as they threw the Christians out of their synagogues.
I decidedly agree with Rabbi ben Zakkai that the LXX with its whole 45-book canon strongly confirms the Christian perspective. That's why he was against it, and that's why I am for it.
Reference: http://tinyurl.com/LXX-jamnia>