I would like to say, I'm very proud that you have started to contribute useful information, thank you. Indeed, the big issue is there is no communication between servers and forums. There are a few dedicated regulars and the admins/ULA/Clan, but more than half of the server population is not represented on the forums.
We shouldn't force players to join the community, but could advertising the forum community on the servers help increase participation on forums? Blackout makes a good point as well, that we don't clearly layout the rules for players on the servers. Since not all players need to be involved in the community, shouldn't we make rules pertaining to the server more easily accessible in game?
This is not only to get the word out to the few players that see the forums, but also to generate ideas on how to truly give players more awareness.