As more LEAs adopted the 40, the price will keep coming down... econ of volume.
As a .40 owner, and one who studied the history of the round, the premise of the round was a balance between the inadequacies of the 9mm in the field,(many precedents when it wasn't enough to stop a lethal imminent threat), and the kick and size of the .45 ACP.
Some refer to the 9mm as nothing but a necked down .38. Just as the .380 is a cut below the 9.
The .40 has more impact lbs. than the 9mm, and faster than a .45. I love them all, and own all 3 calibers. Different strokes for different folks.
It's an evolution, the .38 revolver was adequate in a different time, (Barney Fife, Dick Tracy days), than the .357 Mag, than the high cap 9mm, than the .40 S&W, and as always the .45ACP. The 10mm was/is awesome, but never had the marketing, even when Sonny Crocket used the Bren Ten in the Miami Vice episodes.
The .40 is a good round. And, like all calibers, a 22 can be lethal also, but personal choice is what makes firearms great.
Think of the ramifications if LEO's carried a 44 auto mag, or S&W 500, any LEO shooting with those calibers would be a media field day, there has to be a balance somewhere.
Just, as always, my humble .02 cents