I've never heard "met ed". Clever, though.

It is worthwhile to learn ed(1). It actually has very powerful substitution
and global capabilities, and all of ed(1) is available inside vi(1) with
the ':' (or 'Q') feature, so your knowledge is useful all the time if you 
use vi, and not just when on a console.

Even if you could mount /usr and set your term, it is convenient to be able
to edit without doing that...and it works around buggy terminal emulators.