The M-15 wasn't standard issue for all officers. I occasionally saw a colonel or general with a S&W Model 39 9mm auto.
Of course, upper-ranking officers being so close to their desk and almost always miles away from the "lines" needed these fast-firing and fast-reloading pistols for cracking walnuts, prying off bottle caps with the trigger guard, as a paperweight in their air conditioned office, or to look cool.
Meanwhile, the SPs still carried a 6-shot revolver and weren't even issued speedloaders for them. I bought my own, and my own speedloader pouch, when I was in. Though it wasn't regulation, sergeants and officers looked the other way; they knew it wasn't an affectation.
But high-ranking officers carrying a 9mm that would almost certainly never be fired except at a range was a travesty that still ticks me off.
Some pilots carried the M-39 9mm and I don't begrudge them that. If they were shot down in enemy territory, the 9mm made more sense for escape and evasion than the 2" snubnose .38 that most of them carried.
Nonetheless, the Model 15 was still a good handgun for Security Police. It was light on the belt, utterly reliable, accurate, easy to be trained with and easily maintained.
I loved my M-15 for these reasons, but I also cringed at its capacity limitations and wished we'd been issued the S&W 9mm. Or better yet, the S&W M-59 with its 15-round magazine.
I'd still love to see a commemorative USAF Model 15 made available. It has a long history of service behind that that the S&W 9mm cannot begin to approach. I'm sentimental.