In our travels abroad, you will have noted that most establishments add a service charge to your dinning or bar bills. That is a charge for service. The ten dollar a day charge applied to your shipboard account is not a gratuity nor a tip, It is a service charge, pure and simple. I wish the lines would just call it that. So please try not to relate it to "tipping".
Since the introduction of this charge, the crewmembers have had to commence paying for things like uniforms and accommodation. As many service people have told us, it was felt the service charge would more than offset their cost and result in additional income for them. From what we have heard, we doubt this system is achieving this.
By accepting the daily charge for what it is, we then turn to our gratuities (from the French: gratituude). When we find something exceptionally done for us, we tip. We tip when we want things like ice brought to our cabins at odd hours. We tip at the bars when the service brings enjoyment to our evening not just drinks. And we tip the housekeeping and dinning room staff if they have added to the enjoyment of the cruise.
Everyone knows when they have been made to feel special and have enjoyed service over and above expectation. These are the times when a gratuity is in order.