LE interest in .45 ACP has experienced growth in the last couple of decades.
The last couple of times my former agency polled its few hundreds of sworn/armed members about caliber preference (when ordering new guns), the rank & file expressed a preference for .45 ACP which exceeded 70%. (This was even after inviting people to come to the range and test-fire representative samples before making their choice.)
Each time, however, once the guns arrived and people had to start actually training and qualifying with them, some disadvantages (predictably) surfaced among some of the users. These "disadvantages" were typically the larger grip girth (compared to the 9/.40 guns) and the heavier felt recoil.
From the agency's FTU perspective, it typically meant more time having to help people adjust to the larger grips and increased recoil, which meant more instructor, ammo & related range costs (targets, back-fill for people to attend range sessions, etc) ... or having to let the shooter choose a smaller 9/.40 option (meaning weapon inventory was affected) ... and then there was the cost of the .45 ammo, compared to the less expensive 9/.40 ammo. This is still the case, even though the new CA state contract lists all 4 major LE duty calibers. Of the two .45 JHP's on the contract (HST & Gold Dot), the Speer .45 Gold Dot costs even more than the .357SIG Gold Dot.
Personally, even as a long time .45 ACP aficionado (I own 9 pistols chambered in it), and I previously carried a couple of issued .45's (but also guns chambered in both 9 & .40, over the years) ... from the perspective of being both an instructor and an armorer, if I were asked to wave my magic wand and issue ONE caliber that would best serve the interests of everyone having to carry a pistol? It would be one or another of the several good quality 9's on the market at present, and one (or more) of the newer 9mm JHP's being offered by the major American ammo makers.
The 9mm allows agencies to better utilize ever dwindling budgets for paying instructors/staffing ranges, buying ammo and helping even average shooters improve their skillsets. We're not trying to make Master shooters out of the average cop, any more than we're trying to make NASCAR drivers or authors out of them when we train them to drive patrol veh's or write reports.