With a language, it is far more important. In a gui I can just click around and see. With tuis, I need to enter a command and hope it is the right syntax.
I would spend far less time at my computer (would only use it for work) if it only had a CLI, but I would never, never use a GUI (beyond text editors, of course) for most of the grunt work, the CLI is simply faster and, and this is the most important issue, almost everything you do with it can be automated.
I couldn't even begin to imagine having to navigate the endless dialogues in IDEs to configure every little thing I would do in the command line, I'd give up programming altogether.