If you haven't combined terminal tools together then you haven't use the terminal the way it's intended.

If you start 1 command and get 1 output, the terminal isn't particularly powerful.

One you do start combining commands then it's a totally different thing.

If your GUI does everything you need, then a terminal isn't necessarily useful. If your GUI doesn't provide a feature though, you are most likely stuck. You might be able to learn it's own API in a specific language, e.g. Lisp for Gimp, Python for Blender, etc. If though your terminal application doesn't provide what you need you can pipe its output to another terminal application and thus get something that none of those applications individual can. Once you have done it with 2 applications you can do that with 3, 4, etc. You can label those applications and re-use that tomorrow, share with someone else, etc.

The terminal isn't about starting one application.