- TOTK Ganondorf is a completely different person from the previous Ganondorf's. Which he shares some references, he has no clear ties to Demise. The others are designed so their evil is impossible to go away while the Triforce exists, because it hard ties Ganondorf to Demise. Ironically, this is just as much of a problem for Link and Zelda, but they're cursed differently. PH and ST also muddies this by still having evil that resembles Ganon, despite the Triforce being gone. The official story is Ganondorf lost his ties to Demise when he lost the Triforce. It's possible that Link and Zelda not dying in that battle apparently kept the reincarnation going?
- TOTK Ganondorf is also a much different person. He's a horrific man by choice, but also never turns into a form of Ganon. So this means you already can't use Calamity Ganon as the OOT Ganon boss fight(if they would take HW's unique bipedal one, sure. Though he's still not Ganondorf, as Calamity Ganon is basically a being who came out of Ganondorf's body. This is the only time they're really separate people).
- While they share the same bodyshape(it's hard to tell, due to Models Resource having them at different angles) apparently, this doesn't make it a good alt. The sword is most definitely not going to change how it functions because of the Samurai Blade that the TOTK version wields. That would change his playstyle too much. If it can't be clearly uses identical to his current broadsword, it fails as a weapon choice. Which is saying something, because even the Sword of Sages acts closer to the Broadsword. Almost ironically, considering it's a different kind of sword(but, well, magical sword?).
- A costume reference works, but not if you have to extremely overhaul his functions to justify it. Overall, TOTK Ganondorf is significantly more different from the others. He makes more sense to keep separate if playable at all. And no, it doesn't matter if it's a second Ganondorf(which hilariously wouldn't be a second Ganon since he can't become the actual Ganon, hilariously enough). He's also not as iconic as OOT's either.
- It does make more sense to use Pig Ganon as his own character in comparison, sure. He has an actual different weapon to use, and different skills.
- Finally, the comparison to Link isn't too grand. Link already has functional differences that made him overall worse. The so-called upgrade changed too much in the end.
- Ironically, Young Link is the Classic Link people wanted, but only to a degree. He plays much closer to the previous design since Smash 64. However, you know, not being more of a heavy-to-middleweight, low range, etc. doesn't help.
- The idea a Classic Link echo is bad is pretty silly too. Besides actually functioning like the TP/OOT design more, it gives a better character, more unique options, but also has a modified playstyle that keeps the old one that some prefer. Others will flock to BOTW's design on its own, and that's cool too. Besides, it's pretty much not that much work as some. It's basically just taking the version from Wii U, using him, doing some balance, and at most giving him perhaps a different taunt or victory. In addition, it gives more overall options. The only downside is that they'd need to... figure out a naming scheme that makes sense. Since he's the previous Link, calling him Classic Link is weird. In fact, this is the only actual reason it's not feasible within the design philosophy. It's not a matter of "too much work" or that he won't be popular at all as a choice.
- On the other hand... you just make BOTW Link the Echo instead. What name? Eh, I dunno. You can't go with BOTW Link either way. Wild Link was a pretty good and accurate name in comparison, I guess?
But yeah, you can see why they didn't do so. And they especially wouldn't change Ganondorf that much. BOTW Link actually made Link noticeably worse and less recognizable. It didn't actually work like it could've. It was a cool idea, but just like trying to buff Ganondorf, didn't work that well. Though it should be noted that Ganondorf, despite being his own bottom tier, is significantly more viable than Brawl and 4. In other words, they did actually make him better than the previous games, while ironically making Link worse in comparison. What does it mean? It means trying too hard to "promote the latest design" is not as feasible as people make it. Nor is combining the newest one with the latest one always the right call. Hell, should we need to note how terrible Brawl Ganondorf was? Even worse than how BOTW Link turned out? Yeah. The only thing to say about Brawl Dorf is that he was satisfying as hell to use(and him being a slower more brutish character did legitimately become a more proper portrayal. In fact, that became his canon personality to a degree within the games after WW. They kept going with the spin-offs, FSA, TOTK, and his alternate take in Age of Calamity, which doesn't even have GanonDORF in it. As noted above, Calamity Ganon is pretty much a separate being from Ganondorf this time instead of clearly the same person. But that's more due to basically being a split personality design-wise.
I should note that Zelda is a unique case where they did it right. Not just that she became quite a bit better compared to previous games, but they didn't focus too hard to changing her to the latest version, they updated her in a way that fits her well and made her better. She's the only one to get that kind of update(other than TP Link, respectively) to directly improve their previous game design(Ganondorf is kind of odd in that reverting to OOT, not updating his design, actually did improve him, but it didn't make him anywhere close to his Melee tiers) and improve in the meta. It's pretty clear Zelda characters trying too hard to promote the latest game has a noticeable bad effect on their options. It didn't work. To note further, this is Zelda's best placement in the entire Smash franchise. Because they tried to improve her, not try to "promote the latest abilities".
Overall, TOTK Ganondorf is cool, but he doesn't fit the current Dorf's mold very well at all. Nor would he make, say, a good Echo. A semi-clone or regular clone, perhaps. And that's iffy. He absolutely would make a terrible replacement too, since he's just not similar enough to be an ideal fixover. It was bad enough with the TP one, but he at least still could reasonably function in a similar manner(the loss of speed sucked, and Ganondorf wasn't even that slow in TP. It was a weird armor-related thing that really didn't need to be used that way. Like, he shouldn't be hyper fast by any means. Maybe a tad slower than Melee. That said, Ultimate returned much closer to his playstyle, including his previous functioning style, while still keeping the updated ideas that further benefited him since his design in Brawl.
It's also worth noting Brawl is pretty much the only time Ganondorf got any kind of real overhaul, and it hurt him badly. Albeit, not in the personality department. Just the gameplay one. He became significantly more canon-like, but lost viability hard. Ultimate doesn't really overhaul him so much as somewhat update him(for better or worse), giving him a weapon planned in Melee to use, and give him new tools. The good news is that despite Brawl's... issues, they actually made him make more sense in some ways. Him having a lot more super armor is significantly more accurate to him as a boss character in general. He's a tank, regardless of the pig form or not. His speed loss was the only issue, regardless of its original design reasoning. I do see him improving, but I don't see it through trying to promote an extremely different take on him as a good concept for it.
Like, actually new.
