Well Stephanie you made me feel better because my DH had a good laugh...at me when he saw that I was asking that question.
I say if it will help us sleep better, then, it becomes an essential in the packing list. As a former "stewardess", I remember many who brought their pillows on trips with them.
I bet when the time comes, the DH will want to pack his own down pillow!
I will go further and say that if you cruised on the Jubilee and had a nasty pillow, then the sister ship the Celebration must have the same yukky hard bricks to sleep on.
Have a great cruise!