Re: Efficient interface
The history of vi tracks from this. Once you get the hang of its obscure commands, vi is very powerful, allowing very quick editing with minimal keypresses
The first 'proper' editor I ever really used was xedit on the IBM mainframe which was similarly obscure but powerful (a metaphor for the whole VM/CMS itself and TPF - the OS I was programming for). Designed for use on 3270 terminals that didn't have the concept of interactive screen updates (essentially just a list of screen updates got sent so, in those days of scarce bandwidth and CPU/RAM, you wanted to send as little info as possible which made short commands important).The whole screen got repainted every time there was an update although only the changed fields needed transmitting to the terminal.
We didn't have physical terminals - we ran the IBM 3270 emulator on our PS/2 50/z PCs.. (and not a lot of people realised that they allowed a DOS shell in the background or that they could run quite happily under Desqview..) I still remember that the right-hand CTRL key was repurposed as the enter key so that people who were used to the layout of the hardware terminals could use their muscle memory.
Also the mainframe had Rexx for doing scripting - not that we used it much.