Fillers just isn't about giving the manga time. The anime isn't made week by week, ya know. They already have the entire season made out. Fillers are about the money!! If a season is has 20 canon episodes. You throw in 20 fillers. Now fans gotta buy 2 DVD sets. Out of 40 episodes, 20 are canon.
The more money the anime makes, better the next season will look.
Also, it ensures the anime won't catch up with the manga. The manga is still the blueprint to anime.
If fans are impatience for the next episode, then that means they've done a good job. If they're not impatience, then something is wrong. Very wrong..