Here's a link to a IT Service Management blog. http://www.itsmsolutions.com/newsletters/DITYvol6iss27.htm
The suggestion on this page is to use a 3-level approach - Category. / Item / Type. We used this approach when setting up our WHD application. In addition to the creep you reference, we also thought if a client has to click more than 3 times to submit a ticket they would give up and just email or call the Help Desk.