It's true. You are given a handful of dialogue options and usually 3/4 of them are fluff. I guess Beth wanted to keep it kind of linear because they want the story to flow well into the next installment. I mean, you cant have massive story line shifts and ~5 different endings when you are essentially the second coming of Christ.
To be completely honest, I'd be fine if the conversations ended up in the same place as now; either you accept their task or you don't.
What I don't like is having it be completely one-sided and not having any input on how it develops.
Perhaps I want to extort the quest giver, or convince him of his wrongs, or disagree with his moral standings. It would all (for the most part) end in either doing the quest or not. The only difference is walking away with the illusion of having shaped the world.
I believe this is something TES could benefit from.