If there are several different metrics which you could plausibly report for a situation, then you use the one(s) for which the measured values are the best fit to your agenda.

Because total dollar cost is dominated by major hurricanes, which are rare, therefore any underlying trend would be invisible under the stochastic noise.

Frequency at a moderate severity level is much more stable and can give better insight.

As other posters already pointed out, the severity of the events should be adjusted for inflation, building characteristics, and total exposure.