I can see a rationale for the Premium+ package being priced less than the Premium. Did you ever get a "free" bottle of wine that comes with your stateroom or as a gift from a travel agent. It is usually the absolutely lowest priced wine on the wine list and is pretty awful. In fact, if we already have the premium package with some excellent wine, why bother drinking the "free" bottle? We often just leave it behind when we disembark.
If people drink the two "free" bottles, perhaps they would order fewer premium wines at the bar and in the dining room. Thus, the cruise line may be saving money.
As far as the $50 in casino free play, the cruise line is betting (with stats on their side), that once you start playing, you continue playing. It is highly likely that you will give it all back and then some. Even when people have big wins, more than enough will give it back compared to the few who walk away. Otherwise, the casinos would go out of business.
As far as the minibar in the room, I have no idea. They say they stock the minibar and replenish it daily. But, they don't say that you won't be charged for what you consume. We will have to wait and see what people actually experience.
Thanks to the thread starter for bringing this new promotion to our attention.