Regarding the keywords, for me it seems like adding them as something extra to the dialogue trees allows for the best of both worlds, so long as they don't overwhelm the feel of conversation. Of course, how I feel about it very much depends upon its implementation, which can only be properly judged by playing the game.
So that said, what little I have seen so far looks good to my eyes, so I would encourage people to keep an open mind and allow the alpha testers to provide feedback before summarily dismissing the feature out of hand.
If done subtly, keywords could potentially allow for far greater reactivity without 'ruining' the flow of the dialogue we know and love. I think we could all agree that more reactivity is a positive thing. So let us judge it on its implementation, rather than as a mere idea.
