I will put a flag on the hill that versatility and range in the recoil and "power" of a pistol is of value, and a world where both 10mm and .40 can play.
Getting to that .400" bullet diameter gets jacketed bullets of 135 - 200+ gr, and there's loading out there in all these weights to get supers or subs.
I'll never end up doing it, but I have wondered how nice-shooting of a gun could be had with .400 Cor-bon in something like a USP or M&P that started life as a factory .45.