Why are inverter modules extremely oversized in VFDs?
Those current ratings only consider conduction loss ratings. But there are also switching losses. Even then, sit down and calculate the temperature. It is never anywhere near the rating.

There are also startup currents and peak currents where the heat generated by \$I^2R\$ losses is produced faster than the heat can spread and equillibriate on the transistor substrate causing hot spots.

There are also all sorts of nasty voltage transients.

I was monitoring VFD currents the other day on a scope. For a 1HP, 230V 3-phase motor, startup currents on a single phase were repetitive 18-30A bursts lasting miliseconds while the motor was spooling up. The nameplate current was 2.68A.