GUIs are very valuable because they can do things CLIs cannot, like show you at a glance what operations are available, promote the standard usecase of the CLI etc. Stuff that takes a bit of reading and clever typing with a CLI.
This tool allows you to quickly write a highly specific GUI that is using CLI app in the background.
I definitely agree with this. I think getting people up to speed on how to use a CLI tool would be a great use case for this.
I would probably use more cli tools if there was a clear GUI introduction that shows how the options map to the commands.
This is something that's called out in the main Gooey documentation, but omitted in this this guide: Gooey is made to solve the problem of getting usable software to non-techie people's hands without having to write layers of GUI code or change how we'd write software. The main idea that spawned Gooey was that it could act as an "impedance matcher" of sorts between how I want to write software as a developer (CLI), versus how end-users want to consume software (GUI).
Of course, for scripting and automation you need non-CLIs. And a lot of the time it is faster to use a cli tool, but, for the niche tool that I don't use that much (like mpv or curl), a simple GUI is nice.