In my case I agree with tipping the room steward, bartenders and dinning room staff. I normally get great service and they deserve it. I disagree with them expanding it to others that they should be paying a wage too. It should not be my responsibility to supplement the wages of those that wash the linen or vacuum the common area, etc. I don't do it at a hotel and I shouldn't be doing it on a ship. Everyone is entiled to their opinion and that is mine.
In saying that I will admit that I prepay my gratuities so I don't have to worry about it.