Why That's Too Long:
succeeded so well because it was lean, mean and focused.
The Chronicles of Riddick
did the complete opposite, pumping so much space opera, melodrama and superfluous characters into the mix that it drastically missed the point of why fans had loved Riddick in the first place.
How We'd Fix It:
Remove all the additional characters and sub-plots who brought nothing to the table (Judi Dench, as much as we love you, we're looking at you). So, in other words, a movie that looks pretty darn similar to forthcoming threequel