Actually pricing is per cabin since only one person has to book it for the entire cabin to get it.
Holland America already guarantees this for everyone as early as 11:30 shipwide.
But I still think its a good idea - but you certainly do have a point that it conflicts with the loyalty members.
Once again, it is about making money. I almost hate to say this but watch for this - an annual fee to maintain your loyaty membership status - but they add more perks like this one for everyone.