For the record, Miley Cyrus ain't the way to go. *shudders*
This would be my guess, based on what I know of gamers:
For most people it's a matter of priorities. They have a certain amount of time to devote to DoE. They devote it to the game because that's what gives them pleasure. The forums are going to be where they go when they need information or help. If they have a bit of spare time, they'll cruise through and share some knowledge.
So trying to attract people to post is probably not that easy.
They're here to play, not talk.
There's also the problem of watering down the forum content. Most people don't want to read through lots and lots of extraneous stuff to get to what they need, so it's important that when people post they try to keep it in the right categories and only post once. Otherwise people with limited time get overwhelmed and confused and just give up.
So... It either needs to be pertinent content that they haven't seen before that will help them in the game, a question/problem, or something funny/thought-provoking in This and That that people might take an extra minute or two to think about and answer.
But don't expect miracles, and remember that there are all sorts of players who play for various reasons.