I think the problem is that it lacked a lot of possible fan basis on the most likable of all characters. Me, I felt that it didn't have a decent plot/storyline, there were a lot of dull characters such as Akashi/Bouken Red, Gordom Priest, Jaryuu King Ryuu-On, and Makino-Hakase. But I think Eiji/Bouken Silver and the Questers had the most unique story in the show. Natsuki was uberly the cutest Yellow senshi ever, Zuban was the bomb-diggidy and perhaps they made Souta-kun/Bouken Blue too much of a playboy and I think that was less camera time for each of the Negative Syndicate. Now the movie was cool, but Boukenger vs. Super Sentai was weak for me, no thanks to Aka Red, but I think they should have picked another female Veteran Sentai heroes for the Veteran roster like Deka Pink or Gao White in the place of Deka Break and have Gao Yellow in Magi Yellow's place.
That's about it.