Many terminal users will be upset if you change a tool out from under them. Many desktop users don't know how to vocalize it.
In addition, it's more common afaict for cli/tui tools to be open source, so if someone does change a tool out from under you it's possible to fork the old version and keep the UI you like.
A huge issue with this for me is that it is practically impossible to confine myself to the universe where only vim keybindings exist.
* vscodevim extension for Vscode
* "set -o vi" in Bash
* Vim Vixen plugin for Firefox
* you can use ctrl-alt-j in gdb. And that might (should?) work in other programs which use GNU Readline to get vi keybindings. The only thing I miss with the vi bindings in bash/readline is "ge/gE" from vim (move backwards to the end of the word).
These days, on Firefox, Tridactyl is the way to go for me.