Why are there so few modal-editors that aren't vi*?

Early software was often modal, but usability took a turn at some point, away from this style.

VI-based editors are total enigmas -- they're the only real surviving members of that order of software.

Modes are a no-no in usability and interaction design because we humans are fickle mammals who cannot be trusted to remember what mode the application is in.

If you think you are in one "mode" when you are actually in another, then all sorts of badness can ensue. What you believe to be a series of harmless keystrokes can (in the wrong mode) cause unlimited catastrophe. This is known as a "mode error".

To learn more, search for the term "modeless" (and "usability")

As mentioned in the comments below, a Modal interface in the hands of an experienced and non-fickle person can be extremely efficient.

Um... maybe there isn't much of a need for one, given that Vi/Vim is pretty much available everywhere and got the whole modal thing right? :)

I think that it's because vi (and its ilk) already occupies the ecological niche of modal editors.

The number of people who prefer modal and haven't yet been attracted to vi is probably 0, so the hypothetical vi competitor would have to be so great as to make a significant number of vi users switch. This isn't likely. The cost of switching editors is huge and the vi-s are probably already as good as modal editors go. Well, maybe a significant breakthrough could improve upon them, but I find this unlikely.