First off, we're in our traditional spring slump of attendance. Most people have too much going on in the real world as compared to summer (students on break) or the holidays (which used to include the release of the movies). Secondly, as
Formendacil brought up, a lot of the "Movie Members" who registered just to talk about the movies have run out of things to talk about and seem to be slowly dwindling out. Not to discount those who come for the movies and end up discussing the books; we have plenty of those.
And lastly BW might be
cleaning up old unused accounts, resulting in a lower number of registered posters.
Like
Ainasaid, the Barrow-Downs Birthday Party next month will wake things up a bit as will summer with people having more free time.