Cases are for klutzes.
I also extremely hate Otterboxes with a burning firey passion. EVERY iPHONE IN MY SCHOOL HAS ONE, and 90% of all the iPhone owners are douchebags/jerks/people you just want to punch in the face, so I associate Otterboxes with them.
Otterboxes are also just extremely uncomfortable.
EDIT: I kinda started to stray away from the point:
Cases really take the beauty away from the device. Most of the time they add bulk, take away comfort from the phone, and make them look atrocious.