Source: http://kotaku.com/zelda-producer-explains-why-despite-speculation-the-n-1781973528Kotaku said:Zelda series producer Eiji Aonuma credits fan speculation for the creation of a female Link in the recent Legend of Zelda: Hyrule Warriors 3DS game, but he clarified to Kotaku here at E3 that the Link in the new Wii U Zelda who first showed up in a 2014 trailer was always planned to be a guy.
Aonuma said he had been vague about the specifics of the new game’s Link when he was giving interviews about that trailer in 2014. He thinks that helped lead some Zelda fans to think that the somewhat androgynous Link shown in the trailer might be a girl. Aonuma said his lack of specifics on the character two years ago hadn’t been intended to stoke fan theories. “My intention was to say this isn’t done and there may be changes coming to that. I in no way had intention of leading people into believing Link was female.”
But why not have a female Link in this big new game? “You know there’s the idea of the Triforce in the Zelda games we make,” he told Kotaku. “The Triforce is made up of Princess Zelda, Ganon and Link. Princess Zelda is obviously female. If we made Link a female we thought that would mess with the balance of the Triforce. That’s why we decided not to do it.”
Bit more at the link:During the conversation, which was translated by a Nintendo representative, we asked Aonuma if the rumors of having the option to play as a female version of Link are accurate. He said that he's aware of the conversations happening online, stating: "So yes, there were rumors like that, and we did discuss as a staff as to what would be possible if we took that route."
However, instead of entertaining the idea of the player being able to choose the hero Link's gender, Aonuma said his team considered what they deemed to be the simplest option; making princess Zelda the lead character. "We thought about it," said Aonuma, "and decided that if we're going to have a female protagonist it's simpler to have Princess Zelda as the main character."
This idea was ultimately rejected, because according to Aonuma "...if we have princess Zelda as the main character who fights, then what is Link going to do? Taking into account that, and also the idea of the balance of the Triforce, we thought it best to come back to this [original] makeup."