People have a multitude of reasons for waiting at guest services, and if they want to do it to remove gratuities then that is their right as long as Carnival calls the corporate subsidy "gratuities" and allows its removal.
I personally do not buy into the emotional blackmail that accompanies the ever-increasing burden of tipping culture. I tip what I feel is appropriate for the service I receive. Not triggered at all here.
Carnival's standard of service is so far below what it was just a few years ago I think the gratuity/service equilibrium is in need of correction, personally. And so when I sail, I correct it for my folio.