Why have there been over 125 different updates to the BOM?
Actually, as you can see HERE, there have been more than 3,900 changes to the Book of Mormon.
Of course, according to Joseph Smith, an angel examined his translation and pronounced it perfect. The rather stupid angel was obviously wrong.
By my count, the Utah Church is now in its 10th major revision. The last came out a few months ago when the Church decided it was expedient to alter the Jewish origin of all of the American Indians in light of DNA evidence. Other LDS sects (e.g. the FLDS and Community of Christ) use different versions of the Book of Mormon.
Why is the Book of Mormon copyrighted when the Bible is not?
For the same reason Joseph Smith, Jr. was listed as author and proprietor on the cover page of the original 1830 edition (see photograph above).
For what it is worth, the business aspect of Mormonism has been downplayed in recent decades and Joseph is now presented as translator of the BoM.