Honestly? the Fanbase. The films were alright. They certainly are not able to merit all the aggro the generate.
Think about it, without the new films, the biggest think people like about the franchise right now, the Sith, would essentially be unknown to the largest part of the population. (sure there was always a dark side, but it was the prequels that fleshed out the backstory for the dark side)
Adults who were fans of the original ones not only could not let go that the purpose of the films was to introduce the franchise to a new generation, not to placate the old one. But Nerdrage won out and because of it, the second and third films were never allowed to live up to their potential for too much fear of the fans not liking them and never given anything resembling stable footing.
Think about it, without the new films, the biggest think people like about the franchise right now, the Sith, would essentially be unknown to the largest part of the population. (sure there was always a dark side, but it was the prequels that fleshed out the backstory for the dark side)
Adults who were fans of the original ones not only could not let go that the purpose of the films was to introduce the franchise to a new generation, not to placate the old one. But Nerdrage won out and because of it, the second and third films were never allowed to live up to their potential for too much fear of the fans not liking them and never given anything resembling stable footing.