I seriously feel like the main reason the series has so much filler is that they are contractually obligated to give a certain amount of work to the voice actors in order to retain those actors for the duration of the series. So they need to find ways to bring back old characters, or give sufficient screen time to side characters, and we end up seeing shit like the Part 1 rookies hanging out with Akatsuki.
These fillers feel so random and childish. Everyone is out of character, not of their use of Jutsu makes sense (Nagato's freakout, bringing a building down in an uncontrollable fit of rage just because someone mildly threatened Yahiko, is old example).