I thought the Vox were handled well. They served their purpose, showing how dangerous even progressives with a good cause can become if corrupted by power. The scalps pinned to the board, the slaughtered citizens, etc -- all of this had a point. The revolution was an example of another outcome in another reality, one where the oppressed get the upper hand and turn out to be just as bad in their own way.
Again, I think this is a case where the developers originally planned to do more with them, but ultimately made the right choice in the interest of proper pacing and focus. They tastefully exercised some restraint and treated the Vox as an aside, juxtaposing their noble cause underground in one reality with their bloodbath revolution in another.
Same deal with the Boys of Silence. They're barely in the game, but somehow, it's just enough... Enough to be mysterious, to make the area they appear in memorable, to mix things up for a moment without ever approaching repetition.
Again, probably the most impressive thing about this game, to me, is the willingness to actually edit it, and to cut and trim and tuck where appropriate. Few aspects of the game feel needlessly bloated.