They could have handled the anniversary gimmick better certainly, but imo it seems like the anniversary thing was a very much late addition to gokaiger. The show probably originally was just a One-Piece Super Sentai show before they tacked on the anniversary aspect onto it figuring it'll up the ratings like what happened with Decade.
The lack of attempt to deeply integrate the two aspects of the show I think probably did hurt as did the lack of spectacle.
The lack of attempt to deeply integrate the two aspects of the show I think probably did hurt as did the lack of spectacle.