Training. That just brings us full circle. If they were going to train soldiers to shoot, they wouldn't need a new handgun.
Well the Beretta is getting a bit long in the tooth, and going to a more modern design like the Glock type pistols will have some real logistical advantages. But yeah, if you hit them square, it won't make a whole lot of difference.
And of course, if they actually got their .45's just as soon as they hit the field in real combat, you'd hear people whining about insufficient barrier penetration in comparison to the 9mm.
