I actually disagree with all of what you said. The world building made it feel like an epic. It opened the doors to a whole new rich universe untrapped, where Pitch Black seemed very near future earth and not nearly as interesting in concept. Yes it was great seeing Riddick in the first movie, but it was better seeing him in the second as a super killer take down imperial drones. The necromongers looked fantastic, and were unique in their own way. The third movie just seems to be redoing Pitch Black all over again with nothing really new to add.