35% more energy isnt a significant advantage? If 9mm is the most deadly round on the planet then the gang members beloved .22lr is the second most... but i aint shooting that crap... Again nothing wrong with 9mm but no need to say crazy things to make it sound even better lol... 9mm is good because it costs less recoils less and still usually carries enough energy to do what you want it to do. It is not the end all be all of ballistic science. It is not a magical round that kills better despite much less energy. Its less effective ballistically but the other advantages simply make up for it.
It isn't the "best" pistol round in terms of ballistics, it's just that the other rounds are only marginally better, if at all, to not justify their disadvantages.
9mm HAS killed more people than any other pistol round, and I would bet more than all other pistol rounds currently in service combined.
The only thing that really matters is putting the bullet through a spot on your target that either causes instant incapacitation, or causes the target to choose to stop doing whatever caused it to be shot in the first place. So no, more energy isn't really an advantage as long as it can penetrate enough. All pistol rounds are not guaranteed to penetrate into the human body either, bulllets being deflected by bone, especially the skull, of all calibers is not unheard of.
If you want to talk about the benefits of more modern ammo, like .40, or .357sig, it's not due to higher muzzle velocities or anything like that, it's because they where more often thought out with the intention of making them as JHP, where as 9mm and .45acp where never intended to be made into anything but FMJ.