After I wrote about the fact that guild is mostly empty of people who don't log in except to raid on Tuesdays and Wednesdays, I did some hunting around for commentary on the subject, in addition to hearing from a couple of people. But this post in particular articulates my point best, and is very optimistic in that it's trying to fix the situation and looking for help.
I don't seem to be the only one going through this - there are certainly guilds both on my own server (Thanks, Lal!) and elsewhere (Thanks, Vid!), that seem to be going through the blahs but maybe all of this is symptomatic of something even bigger. There is a feeling of malaise in the game. I can't put it any better than that. I'll try and identify some of the problems I'm personally having.