This might surprise you, but the vast majority of developers manage to get by without learning how to use a terminal. They really do. Saying you wouldn't listen to a developer that doesn't use a terminal is just silly - do you know just how many things there are to learn in the world of programming? Everyone has something they've never learned.
Also - can I just ask, as someone who "uses a terminal" but doesn't really get why people talk about it like it's so amazing - what am I doing wrong? What do you use a terminal for that makes it so important?
The terminal is a relatively standardized display with some severe limitations and kludgyness. The DOM of its era.
The shell, which happens to typically live in the terminal, has three things going for it that GUI interfaces frequently lack.
First, composability and automation: any action you can fire off from the shell, you can fire off from a shell script. Any data you're given by a utility, you can operate on and send to any other utility. Any data you're asked to provide can come from anywhere.
Second, narrative structure with history and a sense of place. "I did X, then I did Y, so now I need to Z... wait, what did X say?" is a natural mode of interaction convenient to many sorts of tasks.
Third, extensibility. Write any new utility (whether in the shell or in any language other you choose) and it is quickly a first class piece of your toolset. (This is the most common of the three to find in GUI land, though it often has limitations).
Also - can I just ask, as someone who "uses a terminal" but doesn't really get why people talk about it like it's so amazing - what am I doing wrong? What do you use a terminal for that makes it so important?