You can't win, it seems. "Service X will never take off, it's confusing because it doesn't look like anything else anyone knows or understands" or "Service X will never take off, it looks exactly like a service people already use and understand and doesn't look like it offers anything new".
As for how this is better/different than email, I don't know any of the email addresses of the people I follow/communicate with on FriendFeed, nor do I want to know. Getting their email addresses is just another hoop to jump through before I can send these kinds of files to them.
I'm sure someone can write a plugin for <insert your favorite email client here> that sends to your whole address book and limits your message to 140 characters. Then we don't need to use twitter either.
It is a cool feature though, and those who can make use of it will, and those who can't won't. Is this going to make anyone switch to using friendfeed? Not necessarily. Will this make using Friendfeed more meaningful for people who are already using Friendfeed for some of their communication? Definitely. Does this distinction matter for every feature deployment? Not really -- at some point in your growth, you can start deploying features that cater to the long tail. Friendfeed's deployment history is to get something out there, see what about it sticks and iterate. Sometimes simple, organic feature announcement, rather than massive fanfares, is a better method (FF has done both). Especially if you're deploying features all the time, not all of them can be epic.