Why has the content of the Holy Bible been changed?
I think for the same reasons.
What contextual changes have been made to the Bible?
Can you list any that change any doctrinal meaning?
Which passages specifically have been changed. We have the manuscripts from which we have our translations and can easily go back and correct any mistakes/intentional errors.
So, which passages were not translated correctly?
Think again...
With each new translation, it was an opportunity for small changes to creep in either to correct grammatical errors or to reflect social changes in language. [Kirkwood, post #145]
Kirkwood, if you think one of the reasons the Bible was changed was to "reflect social changes in language" [post #145];
and, if you think the Book of Mormon was changed for [some?] of the same reasons as the Bible...
...then please explain this:
If Bible translations changed -- for example -- some of the Kings James English from UK of the 15th century is now archaic...then ...
...why did Joseph Smith deliberately choose 15th century Kings James English to communicate to 19th century readers?
Kings James language was fit for some of the phrases in Shakespeare plays of the early 19th century;
And it certainly was read from the pulpits in the 19th century;
as well as in Bibles elsewhere;
but 19th century King English wasn't to be found...
...in the newspapers...
...circulars...
...the overwhelming majority of books...
...in 19th century America or the UK.
And, btw, the overwhelming majority of Kings James language within the Book of Mormon is still there -- it wasn't removed thru the generations since 1830 to "update" it for "social changes."
(there goes that theory of yours)
Hence, Smith did exactly the opposite of your theory: Instead of conveying to readers a translation "fit" with how 19th century Americans wrote and talk, Smith chose a KJV vernacular.
Why?
Well...if you wanted to pass off a counterfeit "addition" to the Bible...what better way to camouflage it?