But IIRC, many European police forces carried the 7.65 (.32ACP) and stepped up to the 9mm because it "was more effective." However, they DID stop there.

I don't know that we have to "justify" the .45 ACP. It has great historical value, did the job it was intended to, and still does- probably better than it did originally due to better bullets. Anyway, most of us accept that handguns are lacking in "stopping power" anyway, so for serious social purposes it really boils down to capacity, and that mostly for LEOs.

And since owning guns isn't all about defending yourself, it's just fun to shoot. 'Nuf said.