I can understand that this could be a totally crucial feature for a subset of people, but I'm not sure "most of us" need the ability to post by email at all times. I've never posted by email once on Dreamwidth or Livejournal, and I doubt I ever will, since I don't use a mobile carrier/plan that enables email via phone -- whereas I'm almost never anywhere that I can't get to a computer. Email posting seems more aimed at the smartphone-toting set rather than the average user, at least IMHO. It makes sense as a paid feature to me.