It's ancient and wierd because it gets the job done even if all you have is a teletype. It's very rare nowadays that you need something that can work in that sort of situation.
Yeah, and it works just as well inside screen/tmux over flaky wireless connections.
I've also successfully used nvi on my phone's ssh client. (Emacs is possible, but its chord-heavy keybindings make that trickier.)
I work on systems over vsat on a regular basis. 750ms rtt at times. Vim is a godsend. I find myself wishing for a good fast 60's style teletype at times.
Have you considered ed? I dimly recall trying a line editor over a slow-slow link and being pleasantly surprised at the difference it made...