Most GUIs can't be navigated by a fluent keybind system. And if they do have keybinds, they are their own, and not consistent with what others use, or you can't modify them. And then there is the issue of making it hard to run multiple copies at the same time (I can't just click the app icon again to start a second copy, Juggler does solve for this though), nor can I keep two copies together side by side easily. Being able to copy and paste text is hit or miss.

I love good GUI apps. They are hard to do well.

Juggler, for example, already collides with a Keyboard Shortcut I use across the desktop, so CMD + J can't be used. It also uses CMD + / for keyboard shortcuts? Tha's a choice. It doesn't respect Mac's preferences/settings shortcut (CMD + ,)

You can be on a chat window, and there is no way without using the mouse that I see where you can start typing into the chat box. Juggler tells me to type / and I can run a command. I type / and nothing happens. What that really means is I have to use my mouse to put the cursor in the small chat box down below.

This isn't to say Juggler is bad. Rather, it's got a long way to go for the GUI to be something that has the fluency of something like vim.

TUIs generally have to solve for that. You have to offer up those features. You can't rely on laziness. So at the very least, there generally are keyboard shortcuts and they need to be obvious.

Feel free to think that people don't have a rational reason for TUIs, but it buys you a lot for free. And this isn't an indictment on Juggler. It works. It's functional. It doesn't feel natural, nor does it respect conventions.