Never did quite understand the point of these other than as a revenue generator for the hotel. What are they saying? That their housekeeping staff isn't honest? That their rooms can easily be broken into by random strangers?

Oh...I know what they're saying:

"Dear guest: We've come up with another junk charge to add to your bill. Even though you didn't ask for this service, you'll have to opt-out of this amenity and the associated fee. We know that most of you won't bother, so we'll gladly keep the extra money! You're welcome, and thank you for staying with us."