Because they're not canonical.

There are two versions of “Apocrypha” ”Apocrypha” (from the Greek word απÏŒκρυφα meaning "those having been hidden away") are texts of uncertain authenticity or writings where the authorship is questioned. In Judeo-Christian theology, the term apocrypha refers to any collection of scriptural texts that falls outside the canon. Given that different denominations have different ideas about what constitutes canonical scripture, there are several different versions of the apocrypha. During sixteenth-century controversies over the biblical canon the word "apocrypha" acquired a negative connotation, and it has become a synonym for "spurious" or "false". This usage usually involves fictitious or legendary accounts that are plausible enough to commonly be considered as truth. In contrast, there is a “biblical apocrypha” includes texts written in the Jewish and Christian religious traditions that either: • were accepted into the biblical canon by some, but not all, Christian faiths, or • are frequently printed in Bibles despite their non-canonical status. A comparative list can be found in the article on books of the Bible. For extra-biblical works sometimes referred to as apocrypha, see the article on apocrypha. The biblical apocrypha are sometimes referred to as the Apocrypha. Although the term apocrypha simply means hidden, this usage is sometimes considered pejorative by those who consider such works to be canonical parts of their scripture. All of the above plus much more on this is available at Vikipedia. http://en.wikipedia.org/wiki/Apocrypha

When the Councils came together, they had a "Criteria for Canonicity" which was: Apostolicity - meaning it was directly from or associated with an apostle Doctrinal Concept - does it agree with both Old Testament and oral traditions of the New Testament Inspiration - unmistakeable evidence of inspiration of the Holy Spirit Universality - universally recognized as a different "calibur" than other writings or other books Moral effect - does it edify, transform, and is it practical? All of those things would be why the Canon is accepted. There are other reasons why the Apoocrypha would be rejected other than the reasons above given. -It was never accepted by the Jews into the Canon. -It was never quoted by Jesus or throughout the New Testament even though they knew they existed. -Contain historical and geographical errors (God cannot make mistakes) -Teach doctrine contrary to the Bible (praying for the dead, 2 Macc 12:44 - prayer to saints, 2 Macc 15:14; Baruch 3:4 - purgatory and redemption after death, 2 Macc 12:42, 46 - worship of angels, Tobit 12:12) -Not found in any catalogues of canonical books in the 1st-4th centuries A.D. -Do not claim divine authority or inspiration The Apocrypha has some historical value as to the start of the Pharisees and Saducees and background on the intertestamental period. I hope some of this helps! God bless you!

It is. My bible's got 73 books. (Same as the 1611 edition of the King James)

Regarding specifically the Deuterocanonicals - for largely doctrinal reasons during the Reformation, Protestants removed seven books from the Old Testament (1 and 2 Maccabees, Sirach, Wisdom, Baruch, Tobit, and Judith) and parts of two others (Daniel and Esther), even though these books had been regarded as canonical since the beginning of Church history.

The short answer is that there are many books and gospels that easily could have been included but weren't. The reason is that they didn't agree with the politics of those editing the "final" edition at the time.