I'd call it preferring good story telling conventions. It's introducing a thing as impossible to undo and then paying off narratively why that impossible to undo thing is able to be undone. TotK and BG3 both say multiple times that their respective transformations are impossible to undo, but only BG3 actually pays off why that's the case when it comes to undoing them.
Still two different approaches, to different goals. And, both do give the
why. Some people just missed it, in one case.
Kintsugi/wabisabi isn't my point, it was just an illustrative example. Broken things can be mended. Physical changes are reversible. Chemical changes are irreversible. This isn't always the case, but it usually is. If you're told something is a chemical change, you wouldn't expect it to be reversible. And if someone reversed a chemical change, it would be surprising. For the story to reverse an irreversible change while emphasizing so heavily it can't be is akin to the stretch of disney films putting every effort into hiding their twist villains before rewriting their characters at the last minute
Issue is, we are not actually talking about repair, when it comes to time manipulation. We are talking about returning something to it's previous state, in alignment with it's own timeline. When it comes to time manipulation, it may still be entirely impossible to causally "fix" something; but having the ability to manipulate time always allows the natural flow of causality to be broken, bent, redirected, cheated, and so on. The whole story revolves around solving the situation with time manipulation. Zelda being flung back in time to help set up Ganondorf's eventual defeat. The Master Sword traveling back to be repaired. Zelda granting Link the recall ability from the distant past, that Link uses constantly through the game. Not to mention the numerous other games in the series that include time manipulation story elements. Using time manipulation to over come an impossible situation is not only an old hat, at this point, but not a big surprise at the end of this story in particular. Zelda sending Link back, with the power of the ocarina, at the end of OoT had less narrative lead up, and I don't see anyone complaining about that moment.
And I have no idea what you could possibly mean by your second paragraph lol. Yes, optional content is optional. There should be an optional ending that rewards that optional content in a connected way
To be fair, much like BotW, the majority of the game is optional. Link's memories of her are not the only ones at play.
I agree that getting all of the memories should have a greater impact on the end scenes, but at the same time, there are three people involved with using the recal ability on Zelda. their memories could very easily fill in the gaps in Link's memories. Their combined powers, their combined memories.
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So, by my count, so far, there are more story elements that tell us that time manipulation is the solution, than there are story elements that tell us that there is no going back from going scaly.
Teacup scene, where we not only get an explanation of the ability, but are told that it relies on the memory of the thing.
The story telling us that the dragon memories are important.
Link being granted recall directly from Zelda, as apposed to the others, highlighting it's importance.
Link using the ability countless times in game play.
the scene where Sonia and Zelda boost one of Rauru's abilities.
Zelda using her knowledge of the future to stack the deck in Link's favor.
The Master Sword going back in time so it can be repaired in time for the final battle.
Then there's the visual elements of the recall ability being used on Zelda at the end, as a final reminder that time manipulation is a thing.
Vs.
Mineru telling Zelda that it can't be undone.
Zelda remembering that conversation.
Zelda being sad about the self sacrifice. (I'm being generous with this one)
The dragons being around current day.
Still going off of memory, so anyone, please, let me know if I forgot anything for either side.