Of course - my daemons and command line interfaces have to produce pretty output, for people who care about other things. But those people are not me.
So I installed Plan 9 from User Space[1] last night - largely on this recommendation :)
Welcome to the world of computing in 70's. Some of us prefer the future. :)
I enjoy GUIs since my Amiga 500 days.
I do enjoy the power of the CLI for automation and pipelining of commands and build scripts.
However I am a visual guy and also enjoy the power of IDEs when coding.
So I rather use the GUI and make use of the CLI when required, than the other way around.
This was exactly how one would use Amiga OS. Spend most of the time in Workbench and use Amiga DOS when required to do so.
Or even the old Mac OS, where a terminal was a third party application. There was no command line, only GUI.
Emacs (and vi) do a wide assortment of refactorings, auto-completions, multipaned outputs, large scale cut and pastes etc. I couldn't think of anything that actually needed graphics. Given that i couldn't think of any reason why an IDE needed to be a GUI.
That is to say I can see people preferring the look, or the use of a pointing device, but I couldn't figure out any coding features that where actually GUI-only. You have any I couldn't think of?
Another nice feature is the ability to see graphical representations of data structures. Specially handy for list and tree based structures.
Design and prototyping of user interfaces.
Amiga OS, Atari OS, Mac OS (X), Windows, OS/2, IRIX, NeXTStep, Native Oberon, SmallTalk...
The Plan 9 userspace excels at tying text-using utils, but the traditional Unix CLI is not the means by which you tie them. Even the terminal is quite far removed from a typical command line.