So the key points.

1. the text makes a huge distinction between a prophet speaking as a prophet and what gets recorded
2. the problematic Mormon view of shifty monks deleting texts is wrong. However the main problem is not distinguishing between the Old Testament composition and the canonization and transmission of the New Testament. Given the OT was compiled by uninspired scribes apparently with conflicting politics they were fighting over out of unknown texts of unknown authority and unknown editing and redaction I think the traditional Mormon folk story fits the Old Testament pretty well.
3. The problem of the NT was less corruption of texts than texts simply never getting dispersed. That is the apostasy happened extremely early.
4. There’s some hints going way back to Sjodahl’s commentaries that the brass plates might reflect the norther tribes scripture rather than the bias of the Josiah reforms Lehi’s enemies faced in Jerusalem
5. That said figuring out where Laban fits in politically is tricky but has a lot to bear on the nature of the brass plates.

And remember, also, that Nephi had already described the state of the Lamanites at that time as “loathsome.” Slaughter, looting, and theft were by no means introduced by Europeans; mass scalped graves dated before Columbus attest to that. It was in many ways impossible for these Gentiles to steal something that had not itself recently been stolen. This was divine judgment, remember, in a way that certainly has much precedent even if it may not have been explicitly proclaimed by the angel.

We can’t reshape God into the being we want him to be. At times he commands peace, at times he commands slaughter. His perspective is longer than ours, and his foresight can turn the most brutal war into a force for good. It can even, eventually, turn me into a righteous man.