That still relates to the actual raid itself, not the release formatting. Perhaps the fights themselves were not as engaging. Bahamut had the advantage of 1.0's legacy supporting it and a storyline that heavily attracted people.

Also, dragons. Fighting dragons never gets boring for some strange reason (personal opinion).

Honestly, I feel it's the lack of variability within this content that causes it to wear out quickly. I have ideas on how to make it engaging for the players and make the content longer-lasting... but it would be a lot of work for the developers to pull of so I'm not sure how feasible it is.