What books are we talking about here? These ones?
Here is a link if you want to read some of the older books:
Pseudepigrapha, Apocrypha and Sacred Writings
I (and all Mormons) agree that the Bible is incomplete...
A Jewish person thinks the Torah is complete... how would you convince someone who is Jewish that more scripture exists beyond the Torah? how would you convince some Christians that more scripture exists beyond the Bible? Everyone can read everything for themselves - does what you read bring the Spirit? the world is full of scripture in my opinion.
The truth is...if we were all illiterate...blind...and deaf...would God or the concept of him, mean any less?
No one needs organized religion or books or churches or priests or pastors or rabbis or anyone at all to discover a connection with a higher power, should they be open hearted to it.
I don't need for someone else to tell me what truth is, for it will only be their version of it. As is the case with all religions.