User blog comment:Omega natsu2/Episode 179: Gray vs. Rufus, Review./@comment-24729244-20140501045112/@comment-7418318-20140501090320

Because of time and money.

They had several month to animate the 1 minute 30 seconds opening. For the weekly episodes of 25ish minutes, they naturally have far less time to work on each scene.

But hopefully they'll get better over time.