CoD's reputation has been on a downward spiral ever since CoD:MW2 was released. That's when people started complaining about CoD losing it roots and deviating too far from the formula that made CoD4 so 'perfect' in their eyes. The gaming community is pretty immature about their hobby and the CoD community especially has highlighted this personality trait in the past. They asked for something new and when they got what they wanted, they said it was crap because it wasn't like the original. Some even took it way too far by threatening developers with physical harm, or death. I think more people would enjoy the newer CoD games, if they would just accept them for what they are and spend some time with them (unless technical and programming problems make it unplayable), learning the little nuances that set them apart from other CoD games.

As for the lack of activity on the site, I think before the release of the latest CoD game, most members have already decided that the game will be total garbage, so they state that fact a few times on the forum, before they get bored with the idea of complaining about another CoD game and just stop posting altogether. This attitude toward CoD has been engraved into their minds for so long now, there's no chance of pulling them out of this slump...