Newspaper Taxi wrote:
Maybe the polling and testing audiences weren't famillar with who Troi and Riker and LeVar Burton were, but if they wrote a decent enough script they could inspire people to care about them.
Nothing to do with the writers, or the moviegoers recognition of other characters, but EVERYTHING to do with Stewart and Spiner's power. They were the most popular characters from the series, and this gave them huge leverage in negotiating their individual contracts when it came to each movie. Both had clauses guaranteeing their characters "arcs" in every film, as well as script input/approval (the latter more for Stewart than Spiner).