[sephoric]

> and people are much more prone to ignore them

I think this is the key that separates Facebook from group emails. Facebook got people into the habit of checking something regularly, so regularly that you could expect that if you post something today, they'll see it within a few days. People never had that habit with email, which is a lot more like mail: you check it when you're waiting for something specific. But you check Facebook when you're bored and want to be entertained with short paragraphs or videos or by participating in gossip.