I've played this game through quite a few times and I've never been denied doing what I wanted to do because of the party's reputation... nor because of the fame score, as far as I know.However, there are several quests I almost always skip, such as the missions for neighboring states - my goal is usually to keep Harmondale independent. (In fact, when the ambassadors arrive and one of them refers to Catherine as "Your Queen", I have the party yell and yell, and then yell some more, in sheer protest of the idea. Doing this really helps.) Perhaps the reputation score has some bearing on these quests?
Alternatively, there could be some bonus to one's ending score, which I've seldom paid any attention to.
