I don't know if it's only me, but rewatching the first few episodes I could see why I was hooked up so much on this series to the point of madness.
It was that the quality of animation helped convey a more dramatic, mysterious, dark and esoteric tone to the story. That reflected on the fights too.
So, what really happened to the quality of animation in Bleach? Has it really suffered?
I think that given the pace of the story and how we as an audience got used to Bankais and Resurreciones, the quality has just got more mundane. The only exception being the fight between Ichigo and Ulquiorra.
But after watching the latest episodes I think it is picking it up.