Very good question.
I would dare to say that most of the problems with the community, or instead, with forums traffic, are all the bugs that have been afflicting these forums for some time now. One of the most nagging problems, notification emails do not work, so you cannot easily track threads. For example, if I want to follow up on this thread, I'm going to have to remember to come and check, instead of waiting for the email to come.
There are also many delays and lock-ups with the forums. To be honest, I cannot believe that these problems have been happening for so long. This is really bad for the image of DNN in general, does not inspire confidence in the product for potential new adopters.
Also, the forum is the entry point to Dotnetnuke for many people, these fixes should have been given the highest possible priority. Even if it is with quick fixes, trying to make these fixes ready for release for the general public in the Forums Module at a time when the main DNN forum is broken I don't think is a good idea. Case in point, notice how long all these problems have been going on.
Another issue, spam blacklists. When the notifications were working some people were bitten by this "problem". Well, the DNN folks should make sure that the accounts, servers, and networks used for those emails are not in any blacklist. In that way we can keep our spam filters fully functional.
By the way, please don't tell me that I don't appreciate the work of the volunteers involved. I do, and I don't buy that argument anyway. These problems need to be fixed ASAP.
Carlos