Hi, you can use it when you are tired and your eyes can't concentrate ;P (joking)
One cool thing about GUIs is that (usually) you can run multiple processes and commands while other processes are running without having to open multiple tabs or shells or to go through the shell outputs to see errors and/or warnings.
But this is not to say "a GUI is better", they are just complementary in my vision.
Personally i use and abuse the CLI for most of the time, because i love to feel the machine is in my hands, then sometimes i feel more comfortable on a GUI or a Wizard process, it' human i guess.