Most on-topic discussions (not related to TLG) have been done to death, and I think that's a huge part of it. Everyone's tired of arguing about whether or not Kopa is canon, etc. There's been a recent boom in activity (by MLK standards) in the TLG board, and several members joining because of TLG, but that hasn't brought up much new discussion for pre-TLG topics, and likely won't.
Plus, most of the members still here are older now and have new interests, and busier lives. I don't know how many TLK projects I've tried to start that went nowhere so I never bothered posting them. I also think it could be useful to have the chatbox on the front page again, but I also forget why it was taken down. I'll bring it up to the rest of the staff and find out.
I wasn't here in 2010, and the forum will never be the way it was in the past because things will always change and such is life. I will say it's much better than it was when I first became active back in summer 2012. It was a mess back then, and I didn't help.

Kops wrote:I'm hoping it's just exam/generally busy period for a lot of members recently, because it's certainly felt very quiet recently.

It does tend to be more active in the summertime, in my experience, so that is probably part of it.