Thank the gods I can exactly predict how this person I basicallly just met will react to everything.
Prior knowledge of how my companions will react to some of my choices really would influence my choice or at least make the choice more compelling.
No, we shouldn't be able to do that.
We should learn about them from their conversations and their reactions to our decisions.
But there should be more reactions from them after we do something they like or dislike to show their character a little more.
More discussion of major and minor decisions back when we're at camp, so they can tell us their opinion on things.
From what I've seen you just don't know the characters well enough yet, if you think their reactions are arbitrary.