Being a stubborn vi user myself I have to admit that almost always the first command I issue, after having logged into a Bash-like shell, is "set -o vi", in order to be the least bit productive at the command line, for I am such a lousy keyboard typer (i.e. effectively only using 6 of my 10 fingers at maximum).
Without the shell's history and vi editing mode I would be hopelessly lost like being jailed in a csh.
But instead of solely having to rely on "set -o vi" there is another relief for klutzes like me.
You can resort to readline by editing a .inputrc file in your HOME (or any other file to which the INPUTRC environment variable would refer to) an put in there the these two stanzas:
set editing-mode vi
set keymap vi
As root you could even set this globally in /etc/inputrc (provided you have no dissenting users) .
Another benefit from using these readline settings is that any program or CLI tool which is readline-gnostic automatically provides you with a vi-style mapping and editing mode, which makes working with these tools equally pleasant.