In my raiding guild, back in BC, A few months before WOTLK it was exactly like this. Everything felt dead, no one wanted to raid etc... I was on one of the most active guild on my server, and we had to recruit like 5 new active raiders a week just to raid Black Temple. We had several recruiters working full time spamming trade chat just to get 5 new active people a week to fill up the people who just disappeared. Guilds merged with us all the time because they kept breaking up and people needed somewhere to go.

So it's no surprise people are getting bored. Ruby Sanctum was pretty much a bust for 95% of wow players.