Real example of why this is a bad idea: www.cs.usfca.edu is not cs.usfca.edu. The latter doesn't even have a DNS entry set up..
A screenshot of the browser will not show the www, making it more difficult to find the website.
A screenshot of the browser will not show the www, making it more difficult to find the website.
At this point, That's just sloppiness on USFCA's part.