I never played the wii U or the switch (with the exception of about 15 minutes) I have been an xbox/pc gamer pretty much most of my life. I want to share my thoughts on the Legend of Zelda series as an outsider (someone who owns zero Nintendo consoles)
The Legend of Zelda - Wii - played and beat
The Legend of Zelda: Adventures of Link - Wii - played and beat
The Legend of Zelda: A link to the past - Wii - played and beat
The Legend of Zelda: Ocarina of Time -Wii - played and beat
The Legend of Zelda: Majora's Mask - Wii - Played and beat
The Legend of Zelda: Link's Awakening - DS - played and beat
The Legend of Zelda: Oracle of Seasons and Ages - DS - played and beat both
The Legend of Zelda: Minish Cap - DS - played and beat
The Legend of Zelda: Phantom Hourglass - DS - played and beat
The Legend of Zelda: Spirit Tracks - DS - played and beat
The Legend of Zelda: The Wind Waker - Wii - played and beat
The Legend of Zelda: Four Swords - GCN - played and beat with friends
The Legend of Zelda: Twilight Princess - Wii - played and beat
I have never played breath of the wind, skyward sword, links awakening remake, and only played a little bit of a link between two worlds. Even though I dont own any Nintendo systems, i have played a lot of Zelda games in the past with my first zelda game being a link to the past. My top 5 favorite Zelda games being...
1. Twilight Princess
2. Ocarina of Time
3. Links Awakening
4. A link to the past
5. Minish Cap
Even though I have beaten most of the series, most of the games I would never replay as a lot of the entries feel the same. I have heard great things about breath of the wild and someday I hope to play it. But honestly... I am burnt out of the Zelda formula, most of the 2D Zelda games offer little to nothing new and if you are a long time Zelda fan you probably feel the same way. Some of the Zelda games I listed above that I beat i had to push myself through (oracle of seasons and ages) so when Skyward Sword launched, A link between two worlds launched, I honestly had no interest in playing them because it just looks a lot like what I have already played before. BOTW is the first Zelda game that when you look at it, looks unlike previous entries and seems to bring the series into the worlds of Skyrim, Witcher, Elden Ring, etc. And is the place where adventure, action, rpg, games have been for a while now. The older formula has already been done so many times before that if someone really wants to play one of those Zelda games theres honestly over a dozen they could just download and start playing. Whereas BOTW is something totally unlike previous Zelda games and if you are or were like me, Skyward Sword HD is not going spark a sudden interest to come back to the series, whereas BOTW will.
This might be one of the reasons BOTW is doing so well, the older Zelda formula was never super popular. It wasn't until BOTW that all that changed, and that was because Nintendo changed the formula. I think a lot of Nintendo fans are just tired of the old Zelda formula and it's reflecting in the sales.