Paladin, I understand your point of view, let me explain mine.
The Gamecube version of Zelda shown in 2000 was a farse. The way that I look at it, the problem was that Nintendo didn't stick to the more "adult" style featured in that trailer. Is Wind Waker a bad game? No. Was public perception hurt because Nintendo decided to go in a completely different direction than what they had led the public to believe was going to be the next Zelda game? Yes. I tend to think that that doesn't happen too often - that when you release trailers and screen shots, or when "Company X" releases those things, they tend to reflect how the final product will look and play. Wind Waker should have been the 2nd Zelda out on GC. If they had any doubts about the direction that they wanted to go with Zelda back in 2000, then yes, it was a huge mistake putting out that trailer.
Generally speaking, though, would you not agree that previews, "leaked" information, trailers and the like generally help a game, as far as hype is concerned?