But there's a few reasons people demand the "dark zelda" game.
1. People who were born in the 80s or early 90s likely grew up with a lot of dark fantasy and kids movies that weren't afraid to make kids cry. OoT and Madura's Mask are not only frequently cited as favourites, but they also deal with dark and heavy themes. Nintendo stood on that dark fantasy line, but never took the final step across it.
2. As people got older, they want more depth and maturity from their entertainment, but they also want the nostalgia and comfort of their old favourites. They won't play Skyrim or Dark Souls because they aren't Zelda. Yet as per point one, Nintendo won't deliver the dark, deep game for adults that they crave.
3. For any younger people that forget, when the GameCube was first shown at E3, it had a Zelda trailer. It was just a graphics demo, but people wanted that game. When Twilight Princess was first revealed with the "blades will bleed" trailer, people lost their minds. There were even stories of people breaking into tears.