moshez : actually, you raise an important point, and one that often leads to much confusion and misunderstanding. What does it mean to say that "vi is usable" ? Many of us find it indispensable to our working practices; next to bash, I would be lost without it. Yet, vi goes against all the received wisdom concerning usability. It is strongly modal; it does no presentation of available options; it has low levels of feedback, and its learning curve is ridiculously shallow.

The answer is of course obvious, but in two parts. First, there is the "zeroth law" of usability: know your target audience. vi is indeed completely unusable to non-geeks[1], but the target audience are people capable and willing to learn its interface. Second, a significant aspect of usability is the efficiency of the interface: vi is a blindingly, hugely efficient way of editing data. This is why we all love it so much.

Most people who accuse UI design advocates of wanting to "dumb down" interfaces start off biased from one of these two points. They either confuse efficiency with usability (one is part of the other, and not necessarily the most important part), or they assume that they are the intended audience. And cue massive flamage.

[1] sorry for the term, I know of none better