As a network administrator the command line is VITAL to my existance. I could do things with the GUI but that takes too long. There are a wealth of utilities that can only be run through it for diagnosing network problems. It is also vital to test run logon scripts before submitting them to user profiles.

And MOST important... Always use the Command Window when doing anything for the big bosses :) If they saw how easy it is using the GUI, they will wonder why they pay you so much ;)