Can you prove otherwise? It's a over 30 years old game, and people 80% of people who own Switch in USA are 34 or less years old:
It's unfortunate I don't have a newer source, these numbers are now 26 months outdated, But they came out when BOTW was around for 1 year already
Of course each game has it own sales demographics, but I don't see why Zelda buyers would be considerably older than average
Plus, even if you're taking into account the newer players (people younger than 35 years) that played the original Zelda in some pirate emulator, virtual console whatsoever how can you make sure these people that played the first Zelda find this specific game design any better than the subsequent Zelda games such as ALTTP, Ocarina of Time, Wind Waker, etc and indeed prefer the first Zelda game to any other of Zelda games?
Seems like the argument you want to sustain is the first Zelda game was loved, they changed the direction due to some console limitations and it was successful for a while (Ocarina of Time) and then people get bored of the OoT formula and wanted Zelda to back to their origins. But honestly, this "return of origins helped to increase sales" point doesn't hold any steam.
I think I agree with what you said about Aonuma's formula making Zelda losing potential gamers. It's true, any game have it's own target demographic and not all kinds of games will meet the same public reception. What I disagree is that backing to their origins is what changed that scenario. IMO, what make BOTW stand out was the incorporation of modern game design elements into its gameplay
People who were Zelda fans loved Zelda they knew, and the Zelda they knew is (mostly) the Zelda of Ocarina of Time onwards. OoT was the 4th best N64 seller for a reason, and it rivaled Mario 64 and Mario Kart 64, so it's quite meaningful. Ocarina of Time for 3DS sold over 6 million copies and it was a storming remaster, Majora's Mask for 3DS sold 3 million copies about the same as the original game. The Wind Waker 2.5 million in a flop system
My only conclusion of this is the "potential gamers" who jumped into BOTW aren't Original Zelda fans/players, they are brand new players who discovered some years ago that open world and exploration games are great and then give BOTW a try because of the awesome world of mouth and reviews. Or even better, it was their first open-world game and again they give it a try because of the already mentioned great world of mouth/reviews.
Agreed. BotW didn't go open world because it wanted to "return to its roots". In fact, even critically, ALttP and Link's Awakening are considered the pinnacle of the series as far as the 2-D games go. Ocarina just took that formula into the 3rd dimension in style and set standards that still hold up today. The formula began to get a bit stale by the time SS came out because of the rise of western open world games.
While it can be said that Zelda is the, or one of the fathers of the open world genre ( Even Ocarina which was linear, was perhaps the first 3-D game to offer the illusion of a cohesive open world, with a night/day cycle, weather changes, extracurricular activities, etc), BotW's direction was inspired by games like Skyrim (which was an inspiration for BotW by Nintendo's own admission)more so than any attempt to return "to the roots" of the series. BotW's amazing reception from critics aided in the massive sales of both the game and the Switch, and indeed many were just people wanting to play the next great open world experience. Many others were Zelda fans from the N64, GC, and Wii eras, very few of them actually played the original.
I am 35, and I did play the first two NES Zelda games but I was a pup then. I managed to actually finish said titles in the GC's Zelda Collectors disc more than a decade later. I was really turned in to a long life fan by Ocarina of Time, more so than ALttP. I suspect the core of BotW owners are actually Zelda fans from that era or TP's era, and rest are new kids who bought the game because as you stated "word of mouth" and the amazing critical reception that the game received.