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.
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.