Jennifer, how would adding $70 to the price of a one week cruise fare per person make it so that only the super-rich could cruise? I doubt that anyone would notice the difference.
It would be a bloody sight better than seeing these tipping arguments all the time.
A tip is not mandatory, it is at the discretion of the person receiving the service, when it becomes required, it is not a tip, but a service charge. Once there is a mandatory service charge, there is no reason for it not to be part of the fare.