Zelda games are epic adventure games and the "art style" helps portray it. Twilight Princess was a very epic game and wind waker seems the opposite of that with its art style. I think we can all agree that Twilight Princess is much more epic than wind waker. Twilight Princess is sells more because it feels like an epic zelda game and captures that epic feeling of the older games. Wind waker doesn't really do that because of the art style and feeling of the game.
The public wants a game more like Twilight Princess/Ocarina of Time and less Wind waker/DS games.