They did a study to find people who had used a pistol in actual combat in the last 10yrs or so. Oddly, almost 1/2 of the confirmed uses belonged to ONE guy who was CQB guy in SOCOM, he liked the Beretta and that was his go to. There were few negatives against it with people who were pistol guys.
However, time was sort of up for it so they wanted something new.
Should ditch the B52, the 50 cal, and the M16 as they all far outdate the Beretta!!!!!
I don't know why this is such a big deal for some. I never used a pistol when I was in the Marine Corps, always a M16A2 that I checked out of the armory. Very few people will use a pistol so this isn't going to affect the majority of the people in the military. As for adopting the Sig, there was no need since the Beretta was just fine and replacing something that works just because it's old is stupid.