Well, I think the sentiment might be that it's more easy to relate to the PT's political story than the OT's political story. What I mean is, most of us who post on these forums don't live under a dictatorship. But many of us do live in democracies and experience the day to day frustrations as a result. Thus, I think it can be easier to get involved with the PT's political story (for some) because we can see why it might turn out the way it did, particularly for those who live in the US. We live in a state of perpetual war where nothing seems to get done due to inefficient bickering. You'll find a lot of people who might feel as Anakin does in saying that those who don't agree should be "made to" by "someone wise" for the common good. It's politically naive, of course, but I think it resonates well for a lot of people because we've all felt that way at one time or another. You don't necessarily need the OT to see that story through to the end as the PT is, in part, about the dangers of choosing the quick and easy route instead of actually learning to deal with the inefficiencies of democracy. The OT has a political story, but it's much less prominent. It's largely nonexistent in ESB and most of ROTJ. ANH is really the only one that delves into it on more than a surface level. And, of course, you have to specify what you mean by "done" -- if someone just wants to watch the fall of the Republic, then the story is basically done with by the end of the PT.