Poor casting, lazy dialogue, lack of a plot, confusing camera decisions (e.g., car chase scene and constantly having camera directed at bright lights), and too long of a movie.
The director should not produce another Batman movie and all primary actors should be recast.
As many people tend to have poor taste in movies and continue to watch and provide profit for unoriginal Hollywood thought (comic book turned movies, remakes of any important historical item, and sequels to originals that werenโt good in the first place), it is unsurprising that so many people enjoyed this terrible movie.