"...but not something that couldn't have also happened with a slightly larger bullet."
The reason for my conjecture is due to increased velocity (300 fps) of a somewhat larger bullet (about 25%) which should cause greater turbulence and wound damage.
Of the crime scenes I am aware of where a victim used a 380 vs a larger caliber, the larger caliber always stopped the good guy. Not a scientific survey, just an interesting observation.
"Also, what makes the .32 ACP a better cartridge than the .380 ACP? "
For most shooters it means better accuracy due to less recoil, faster follow-up shots, and in my tests with various media, the 32 ACP cut slightly deeper.
In fact, fixed barrel 380 pistols are snappier than several of today's new 9mm para pistols...ie the Walther PPS.
The 380 is a marginal cartridge and takes great skill if used against a capable determined assailant.
For 20 years the sea was my home, always recall the sun going down, and my trusty friend, a 1911 pistol, strapped to my side.