Your confusion is caused by conflating two effects: the reduction in impacts from extreme weather driven by improved technology and scientific knowledge, and the increase in impacts driven by an increase in the frequency and severity of extreme weather events.

The reductions you discuss are attributable to the first of those two effects. Climate change drives the second. If we mitigate climate change then we can spare ourselves the increases attributable to the second effect.

You may reply that the first effect can always outpace the second, but I hope with some thought you can recognise that there is no evidence to support that claim, and it is essentially just an article of faith.