Given that both of these planes took-off well within the acceptable safety margin, I’m not sure you can say that the planes deviated from their expected acceler

Given that both of these planes took-off well within the acceptable safety margin, I’m not sure you can say that the planes deviated from their expected acceleration profiles enough for a model to confidently say there was an error significant enough to justify an abort. Ultimately the issue was noticed not because a single plane suffered a failure (one that’s expected to occur occasionally, and where multiple mitigations exist to ensure the failures are safe), but because two planes one after the other suffered an identical failure, a failure that’s only expected to occur rarely. So ultimately the unexpected event was two closely spaced expected failures. Not the expected failures themselves, which kinda indicates that aborting to prevent the expected failures would have quite a high false positive rate. Aborts and alerts with high false positive rates are themselves safety issues which need to be avoided, so a trade off needs to be made. The fact that the individual tail strikes themselves were completely safe, if not ideal, and the larger issue was rapidly recognised and corrected, strongly indicates the right trade offs have been made.