I believe are overthinking it a little. The game was probably designed with Wii U specific features (like every other first party Wii U game) but they were cut once the Switch version development started. The more likely reason for version parity is to avoid confusion, not make people choose, and to not potentially have "better" features on the old system. Think about it... making people choose between portability or touch controls. Not good. Or remember how people preferred the GCN version of Twilight Princess because it was a very different experience? I bet Nintendo didn't want to do that again either.
And the Wii U failed. Who cares if the game was developed "as intended". Consumers did not want more Wii U type experiences. Putting the focus on the portable nature of the Switch was a smarter move, and probably just plain better for a lot more people.
I honestly know about 10 people that bought a switch, and not a single one was attracted to its portability. That's what turned most people off that I know. Especially since they are Nintendo fans, they already own a great portable from nintendo, & many believe Nintendo when they said it's not replacing their current portable line. When has a 3d zelda (mainline game, basically) ever been about portability? What about BotW makes you think Nintendo focused on the portable nature of the Switch in regards to that game?
Twilight Princess on GameCube is my favorite Zelda game, and was a better, more natural experience than the Wii version that was devolved alongside it, after the GC version was over halfway finished. They forced a right handed link in so kiddies could waggle, but everyone who played both could tell that one version was developed as intended, while the other was a little forced, is the best way to put it i think. In that case, Nintendo didn't remove things that were designed for the GCU version just to make the Wii version stand out. To say Nintendo cares about parity when they develop games on multiple Nintendo platforms simultaneously just isn't true, else there would be no smash Bros 3ds/Wii U, hyrule warriors on both, and even the upcoming fire emblem game on 3ds & Switch (which I doubt will have features removed for 3ds so the switch will look like the better version). Nintendo has done this before, as you correctly pointed out, so they're no stranger to making games that take advantage of each of their system's unique gimmicks. To say one would have to choose between "portability or touch controls" (regarding the BotW versions) is a strawman argument. If I own a Wii U, I get the touch screen features. If I own a switch, I get touch screen and portability (for arguments sake, since I can't fathom why someone would prefer a huge rpg to be portable). Why would I have to choose? The chance that more than 1% of Zelda fans would actually buy both versions to compare the two is extremely slim. If one has both systems, you get a choice (choice is a positive option, not something you are forced to do, in this case), but that's only IF the game had been developed as intended for both platforms. Not after one version has been penalized because it may outshine another version. When has Nintendo ever gone so far to create an illusion that one version is superior? Usually they create the games, maybe add new features for new consoles, and let them coexist, and shine on their genuine strengths & weaknesses, as sales are sales & the proceeds of both games go to the same Bank account.
They are cannibalizing their own to convince, who, the gamers? For what reason? The gamers can decide for themselves what they like. They are doing it to convince themselves, as they know they continually market co op experiences (Wii U & Switch have that in common, btw), hoping to catch lightning in a bottle again, while they are embarrassed by their adult fans that actually buy their products with their own money, prefer a console that can compete with competitors consoles from 2 generations ago, has a robust online component (which Nintendo denied anyone wanted until recently), and could care less about motion controls or portability, when they already have a portable gaming line of consoles. Nintendo is either trying to fail, trying to troll, or has been living at neverland ranch cuz they believe that someone wants to look at a 6 inch screen with their friends, & play games with a deformed little half a controller with analog in the middle of the controller (and there's only one, so no FPS, or any of the most popular multiplayer genres), and play crap that is more like a board game than a video game, whereally they break out Microsofts rumble feature so we can see how many pieces of ice are in a glass. What the heck do the people that want to do that kind of stuff need a darn scalptastic $500 console for? They can do all that without it.
Sorry, that was not all directed at you. Nintendo is to me as Donald trump is to progressives & I'm just venting.
P.S. The Wii U failed because Nintendo was too conceited to publicly, officially, release clear & concise messaging that ensured the bandwagon folks like grandma, uncle Charlie, and little Billy's mom knew the difference between the Wii & the Wii U when they looked in the newspaper, or behind the glass at WalMart and MAY have noticed something was different about the one they caught a glimpse of & the one they had at home for the past few years, but Nintendo thought their ultra-successful project was so ubiquitous that people couldn't help but know the intricate details of such a remarkable representation of the future of videogames. Many casual players only turned it on a couple times a month at first, then less & less as time passed & friends stopped coming by just to see it. Those casuals had no problem with that purchase, and most had no clue that the more serious "gamer" would spend 14 hours a week playing games on one. The casuals saw it like a VCR, or a purchase in that realm. Little Johnny's mother had a slight advantage when it came to being informed, as she has tried EVERYTHING to keep Johnny off of it until he does chores & homework each day, but with no success. She may know the difference between the Wii & Wii U, but is starting to see the gaming habit in a bad light since her son seems to value his time on their Wii over life itself. Many parents go through that, and after he learns some boundaries, she wants to surprise him with something. Even being a little more informed, people like her see this console with the exact same name, but it has a "U" after it. She watched videos they have on display at Best Buy, even to see what she can learn, since she doesn't want to disappoint her son by buying him something he already has, and those videos all show everyone using the same Wii-Motes & accessories as the system she bought him a few years back. Those more informed parents thought it was just a game pad accessory that you buy for the console he has (and that is seared into her brain since she and many other parents went through hell to buy a Wii for their kids. In what seems to be a sick joke, Nintendo released the Wii's before there was significant stock available to ensure most of the customers that wanted to buy one, could do so. Because of this, scalpers had a great time charging a full 200 - 250% markup to unsuspecting parents that were just tired of driving all over their state, only to come up empty, so LOTS of these parents paid that exorbitant rate. In addition, Nintendo thinks that out of the 100+ million Wii's sold, that most were non traditional (or "casual") gamers, which is most likely correct. What Nintendo fails to understand is that since the Wii got swept up into popular culture, the people that bought them were not people that were likely to ever buy another console again. They had fun and they moved on, as is customary with pop culture fads. Every single musician, actor, etc who gets insanely quick fame & fortune due to this phenomenon thinks, just as Nintendo does, that it was their talent, drive, or superior intellect that caused this once in a lifetime circumstance to be. They will try for the rest of their lives to satisfy an impossible standard that they credit themselves for creating.