It seems like internet forums as a whole have slowed down. I do agree, I think the quick availability of information through a Google search is partly to blame. Unless you're asking a question about something that just came out a few days ago, chances are the question was answered months or even years ago. I do know that when I got into the hobby back in 2007, nearly every search I did led me to a post here on RCU. These days, similar searches tend to lead to YouTube links and official forums. RCU posts tend to be on the 2nd or 3rd page of search results.
Then on top of that you have social networking sites, I can't tell you how often I see a friend ask a question in their Facebook status that would have probably been a forum question a few years ago. I think people are obviously more comfortable asking the people they know rather than the total strangers on a forum.
And then there's the site itself. I quit posting because I just didn't have a lot of time for the RC hobby anymore, as much as I still might enjoy it. But prior to that, I remember a lot of issues with posting. I was constantly writing my posts in Notepad because there seemed to be a 50/50 chance that whatever I'd written would disappear when I hit the "Post" button.