Why do I have to change my password?
There are many reasons you should change your password on a regular basis, but it all comes down to the fact that the security of your account is more important than you think it is, and that an "attacker" can obtain your password in many ways.
Gustavus is not alone in requiring regular password changes. In fact, most colleges have had such policies for years, and our one year time frame is relatively generous.
Other colleges' explanations
Since other institutions have explained these same concepts, and in order to show that we are in good company in having such policies, here are some links to other colleges' explanations: