You've got to remember that decisions like this are usually made by administrators far removed from the training range. Nobody asks the departmental armorer what's best when they make the order for X,000 pistols.
And really, there's a strong pull to seek out equipment that reduces the amount of training required. You have to pay people to go to the range, pay for the range (indoor ranges that meet modern standards are hideously expensive to build and maintain), pay for rangemasters and instructors, and then pay for the ammo. On top of that, you have to pay for departmental armorers (assuming you don't contract it out), spare parts, spare magazines, and so on.
On top of that, you have to select a firearm and chambering that won't have a disparate impact on female or small-of-stature male officers. Not everyone can carry a full-size 1911 and comfortably ride in a car with it. And by the time you get to the shooting portion of training, departments that pay for recruits to go to the academy have already invested a lot of money in each person. It's a big waste if they can't pass shooting quals.
So it's a position that's not totally without merit--having an easy-to-use pistol that fits many different shooters. The problem is when it's applied by people that really don't have the best grasp on the situation.
True story: Back in the day, it was common for departments to reward top-scoring academy recruits by issuing them or allowing them to carry jazzed-up versions of the standard issue weapon. Different barrels, finishes, grips, adjustable sights, and so on.