Nintendo ditched a bunch of traditions and norms from the Zelda series when they created Zelda: Breath of the Wild. One of the most challenging changes came from Link's redesign. While you can get Link's classic tunic/hat in Breath of the Wild, the character starts out looking quite different. In the Zelda: Breath of the Wild art book, various devs on the project explain their new approach to Link.
“Link is the game’s protagonist, so I’ve always thought we need him to look cool. Yet, if we overdo it, the people playing the game might feel like they’re controlling an already accomplished hero, which I felt could get in the way of the players immersing themselves in the game. For that reason, this time I decided we should make Link a more neutral character in a variety of ways.
We thought that the iconic green tunic and hat had become expected, so we wanted to mix things up and update his look. Interestingly, though, nobody on the team said, ‘Let’s make him blue!’ It just organically ended up that way.”
“Producer Aonuma-san declared that we would be revising expectations by updating Link for this game. He wanted Link to be a more neutral character that players could see themselves as. You can feel how energized and excited the artists were about this idea from the really interesting modern concepts they drew. There were close to one hundred designs presented within the team for Link, and the number of sketches was too great to count.”
“The Link of this game was to be a traveler from the frontier who exudes a sense of adventure, which is why there are a lot of designs that feature capes and bags.
At the beginning of development we drew a lot of landscape concepts. Link wearing blue clothes appeared pretty early on because the blue stood out against the backgrounds we were producing.
Did you notice that the Champion’s Tunic that appears on page 60 (see below) has a different pattern on the chest than the one from the start of development? Since the tunic is unique to Link, it ultimately ended up being a symbolic representation of the Master Sword. The story behind the Champion’s Tunic is touched upon in the second DLC, ‘The Champions’ Ballad.'””