In GUI-land, this is hardly ever the case. I can't compose different software together, which is something I do all the time with the shell.
There are certainly some tools that work better as GUIs, but there are also tons and tons that really are great as terminal tools. No, this may not be a very approachable design for the average non-terminal-user, but that doesn't mean we should decry those who will find it useful. It's okay for different people to use different things.
I think I don't agree with the top-level comment in this thread that "everything should live in the terminal", and instead I believe what another response to that comment said: "everything should be exposed to the shell". Being able to compose tools is a huge productivity gain for those of us who care to do it and are used to it.