They didn't seem to be creative with dialogue. In New Vegas, being a big dumb brute gave me a whole ton of new (stupid) things to say, and it was pretty fun. I haven't seen a single good line in 4.
I have the same feeling. In previous games playing with low or high intelligence was opening new ways to talk and finish some quests. Here high charisma and intelligence is adding one additional option which let you gain more caps as a reward. Sometimes it will let you end quest without a fight but it's rare.
I was thinking to pass F4 couple of times trying high and low stats but I see it won't change much. My brother is playing on the minutemen side and he sees about the same. For some reason almost all ends on fight whatever you do.