RCCL does allow up to two bottles of wine per stateroom. How they monitor this? I don't know. Most of the time they depend on the Port employees to monitor it. I have know people that bring this and more on.
While you do have to pay for the soda package or buy soda by the glass, you need to think of the price difference you're paying in booking RCCL vs
DCL. I love the soda package. I can go up to a bar or the drink machines and get one for free. With Disney, you can only get the free sodas at the drink machines or with a meal. If you get it from a bar, you will still have to pay.
As for the rest of the cost adding up, they are there if you want the items. It's not as if they make you purchase them. The extras on the Liberty would be Ben and Jerry's ice cream, The cupcake shop, Starbucks, and the specialty restaurants. When I was just on the Freedom, we ate each specialty restaurant once, didn't get Ben and Jerry's or a cupcake so our additional out of pocket cost was very limited.
I think in what you'll pay in the extra cost, you'll make up with all the other things RCCL offers like the rock climb wall, the ice skating and the flow rider. I always tell my clients to go with an open mind (as it's not Disney) and you'll enjoy it.