I think the reason Trek fans don't know what they want is because they are a more fluid fandom. There is so much more material available to them that often, each fan has substantial preferential differences. Maybe they liked half of this series and season from this series, and only a few episodes from this series.

Star Wars fans generally match up in more polarized groups because rather than receive a lot of material, we've mostly just gotten rereleases of the same material with some sort of superficial alteration. I'm sure that if Trekkies were limited to the first 6 Star Trek films, and saw them go through the same things we've dealt with, they would know exactly what they want.

To be honest, if the PT hadn't been such a let down, Star Wars fans would probably be even more united in their opinions.