I still maintain that, on average, Carnival cruisers will drink more alcohol than Princess cruisers. That alone explains Carnival's alcohol package costing more on Princess. But we have already seen one increase in the cost of the Princess packages and I wouldn't be surprised to see more.
Princess Platinum and above get a 50% discount on WiFi, so there's that.
It seems like more people threaten to pulls tips on Princess, so that is one reason for Princess to bundle them into packages where they can't be removed.
As I've said before, Carnival Corp offers a number of different cruise lines, with something for everyone. Choice is good.