Redundancy.......I have been on Aikiweb since it's inception......98% of the topics have been brought up before. Combine that with the issues that Jun mentions and it is not the same place that Jun originally established. Interestingly I saw Aikido Today Magazine go through a similar transition....
And we see where Aikido Today is...today
The proliferation of search engines has really changed the need to collect information, even information from a small niche activity, into a single location.
For example, the dojo search function on AikiWeb, which has to be updated manually, is usually beat out these days by local search on the major search engines, IME.
Most of the stuff on AikiWeb isn't new. Most of the places right now that are hosting successful online conversations are ones that are either fed continously by new content, or are places where people are looking for specific advice for new situations (ie, the chicken site that Cady mentioned). Even the advice based sites tend to go stagnant once most of the major issues get covered (you can see that happening as a site ages).
Another part of that is that there really isn't much new information coming out on Aikido in general these days. If you look around the internet, search on blogs, etc. - most of it is rehashing things that have already come up over the years.
Even most of Stan Pranin's stuff (which I love, don't get me wrong) is mostly recycled information interspersed with a few opinion pieces.
There's nothing wrong with that, I guess, leaves more time for training...