I think if you're doing the same task a lot then a command line based workflow can be very productive. However, the big advantages GUIs have is that they allow

I think if you're doing the same task a lot then a command line based workflow can be very productive. However, the big advantages GUIs have is that they allow the discovery of new functions. Reading the man page for a command line application is complex and often quite confusing, while a well designed GUI will often allow you to easily find the functionality you want with a tiny bit of trial and error.