With water you can advertise purity and maybe some minerals or additives. You might advertise the uniqueness of the source, but I think you get limited by the whole H20 thing.
With wine you can bring in the uniqueness of the grapes and the growing (read weather) conditions in a particular little piece of land on the Earth's surface in a given year. In addition to the arguments about the raw material you can add differences in fermenting, bottling, etc.
I think wine has a much better set of facts to build a marketing story on. I'd imagine with sufficient technology you could make some really good and standard wine but then the story aspect would be weakened.
This isn't to say that I don't think water markup (30$ a bottle) isn't an extremely impressive display of marketing. In terms of a difference between the cost of the base product and the marked up product water is probably even more amazing than wine. I just think that, in commanding absolute amounts, the scarcity arguments for wine probably make a better story.
(link is NSFW in stuck-up places and cultures)