@Leon: Great answer.
@dbr: Modal editing is something that takes a while to get used to. If you were to build a new editor that fits this paradigm, how would you improve on VI/VIM/Emacs? I think that is, in part, an answer to the question. Getting it "right" is hard enough, competing agains the likes of VI/VIM/Emacs would be extremely tough -- most people who use these editors are "die hard" fans, and you'd have to give them a compelling reason to move to another editor. Those people who don't use them already are most likely going to stay in a non-modal editor. IMHO of course ;)