Personally, I would rather tip on a service rendered basis. I would rather tip the lunch buffet staff that seat me and tip my dinning room waiter for services rendered. Often, I only use room sevice. I generally keep a stack of ones to tip them two or three dollars.
I always tip the appropriate people the appropriate amounts; I generally tip 150% or so of the recommened amount - but only those that exceed my normal level of service. I give my favorite bartender $20 or so at the end of the cruise and the Matrie'D (sp) $20 if he/she makes sure my table is OK.
If the water person leaves me stranded for 20 minutes one night - I evaluate why. If it is two or three nights, he/she gets zilch.
Tips are supplements to income I understand, but they are at the discression of the tipper. For example, on a 7-night cruise last year, our group of ten gave a combined wopping total of $10 to the waiter. The head waiter got $500 - he took care of our group.
Last month, I gave my waiter $130 when the recommended was $90, the waterperson received $20 over the recommended. The staff all received more than the recommended because they rendered services exceeding the norm.
I have "stiffed" many service persons in the past. In fact, I show up at the last night and I proudly hand over my $1 in the envelope That is the way I handle it. Of course, I ship the money due that person to someone else that gave me exceptional service.
I agree with pre-tipping as a concept so that people aren't surprised with the dough at the end of the cruise, but it must have an adjustment policy because some people just deserve $1 and some deserve all the money.