It doesn't change the risk (benefit) side of the cost/benefit equation, but it does change the cost side. To illustrate why this matters, imagine a more extrem

It doesn't change the risk (benefit) side of the cost/benefit equation, but it does change the cost side. To illustrate why this matters, imagine a more extreme situation, where it was somehow discovered that a similar flaw existed in all Boeing and Airbus jets. If a single new jet were being developed that had a similar risk, it could be enough to prevent certification, but we wouldn't stop all air travel because of it - the cost would be too high. Grounding just MAX jets obviously wouldn't have that degree of impact, but the cost to airlines and to passengers would still be significant.