In the Linux world, sure. The only reason why I've seen nano (rather, pico) on many non-Linux systems was because pine was installed, and that was only on multi-user systems.
On a personal level, I am not going to disagree with you. I configured Pine to use vi (or whatever vi variant shipped with AIX). I also seem to recall configuring lynx to use vi to edit forms (which made using web based forums bearable).
That said, editors are a personal thing. Pico was certainly a better choice for most people. In most cases, their needs are basic. Pico also displayed the relevant keyboard shortcuts on the bottom of the screen. Why would they want to complicate things, and vi would complicate things for people who did not have a need for a text editor outside of composing emails.
