Unlike forums or email lists, Facebook seems to be more like a carousel. People get on and off at different times. Maybe they'll see your post, probably they won't. Depending on how many "friends" are involved, the sheer amount of posts coming on stream is overwhelming. Of course, if you're willing to pay Facebook to promote your post you'll no doubt increase your visibility. I'm not.
Facebook traffic is not the same as forum engagement. Unfortunately, forums seem to be struggling in the current social network dominated landscape. The ease with which people can post photos and videos to Facebook is tough for the text focused forums to compete with. Simply put, more people prefer looking at pictures and movies than they do reading sentences and paragraphs.
I've spent some time considering whether or not it's worth it to me to invest the time to make my sites more visual. At this point, I've decided not to. Not that I don't think having users be able to upload photos would be a plus, but the truth is, I'm not sure it would make that much of a difference.