Mike,
It's true that the level of dues isn't a matter of principle, but it is related to one's beliefs about whether the party's activities should be controlled from the top down or from the bottom up. The more money the national and state offices get from members in dues, the less money the members have to spend on the projects they prefer. Also, if total revenue is maximized instead of total membership, fewer people will be choosing delegates and voting on policy.
Kelly