The main difference is that if you manually click that button, without having synced changes you made on another device, then you caused the sync conflict yourself. If the app clicks it for you, then any resulting sync conflict is Anki’s fault.
In your proposals, you seem to be assuming that the problem is that this device hasn’t been synced. Often the problem is that something happened on another device that hasn’t yet been synced – and that can’t be solved from this device. You also seem to be ignoring the additional sync-load that would come from re-optimizing daily/every sync. That’s an actual delay that is visible to users, and would have a significant impact on the AnkiWeb servers, and users with limited/throttled/slow internet.
Not every user has perfect sync habits – even users with auto-sync on open/close available to them (i.e. on desktop and AnkiDroid). Making some change to certain notes/cards/scheduling on one device when you’re out of sync is usually not the end of the world. But FSRS optimization updates the state of every active card in your collection, which means you should expect sync conflicts would become more noticeable and more harmful.
Anyone who has proposals for how to crack this nut needs to start by accepting that sync conflicts are common and can be incredibly disruptive to learning. They are certainly a more significant issue than the unfortunate hurdle of needing to manually optimize your parameters every once in a while.
And then when thousands of users enable it (after Expertium or AnKing casually mentions that it exists …) – are you offering to provide support to help them deal with the fallout? Don’t forget that there’s no real solution to the sync-conflict issue, and sync conflicts can happen to anyone, even the most sensible of users.