Recently at the Hilton Atlanta (yes, I know this is the Marriott forum), the staff could not understand why and seemed put off that I did not want to stay in a room where the deadbolt would not engage at all.

That said, I really dislike the properties who program staff keys to override the deadbolt. I fully understand having an override mechanism in case of an emergency or if the lock dies, but to allow the housekeeping keys to override the deadbolt is poor form in my opinion.