I agree both with Todd's arguments and with the rest of the answers, so I'll try to wrap it all in a way that makes sense.
Technically, water is challenging and requires lots of resources. It has a lot of gameplay potential, which is good, but it's also the cause of its cost. That's why I think that "water-related-stuff" shouldn't be developed before launch.
On the other hand, some parcels just doesn't look good enough without water. And that's why I think that simple, non-functional, water should be ingame before launch. Ankle-deep, suffocating state,... Anything would do.