Limited space.
Why isn't the Book Of Jubilees in the Torah?
Not sure, but they have set aside the commemorative food for the holiday celebrating this book:
....Part of the problem with the Book of Jubilees is that so little remains of original writings that there is no way to determine if the book as it now exists is the same book that was originally written. This is one huge reason that the Book of Jubilees fails the standards of the "canon of Scripture."
www.gotquestions.org/book-of-Jubilees.html
And from an internal link from that page:
What measure or standard was used to determine which books should be classified as Scripture? A key verse to understanding the process and purpose, and perhaps the timing of the giving of Scripture, is Jude 3 which states that a Christian's faith “was once for all entrusted to the saints.” Since our faith is defined by Scripture, Jude is essentially saying that Scripture was given once for the benefit of all Christians