Le Champagne has two offerings: $30 charge and the $200 charge with the reserve wines. I have no problem with the $200 charge because, as you point out, there are some very select wines offered. Not sure the $200 is proportional to the wines, but I don't think it needs to be.
Oceania Marina does have an exclusive evening which, I think, will actually be a more exclusive experience. But while Oceania doesn't market itself as inclusive, there are things that even when inclusive extra charges...even significant ones...are justified.
As another example, I have a group on the Celebrity Century next month and the group has bought out Murano for the evening. There is a fee for the restaurant and a guarantee on the liquor/wine purchases.
Yes, exclusivity has its justifiable price...but I guess the question for everyone is..."What is it you think is a justified additional charge and what isn't on Silversea"