Yeah, but Yamato’s connection to them is just standard Strawhat. Standard for a lot of characters really, not just the Strawhats. They “failed“ in the past, but passed their dreams on to be fulfilled in the present.
And if they want to adventure, they get to go on a adventure.
And with Ace and Oden, their deaths were cruel, but Oda still at least gave them a few years of happiness beforehand. Yamato’s life would be the most miserable in One Piece history if she died here, she’d have had twenty eight years of hell and one day of joy- two if we count the day Ace showed up.
It’s not how Oda does things.