I believe the influx of "Wonder 9s" with newer shooters and reloaders has cut into 45 ACP sales. Some who only reload for money reasons go with the smaller cartridge because components are cheaper. Many new 9mm striker fired, "plastic" pistols are cheaper than a full/normal sized 45 ACP. Many are recoil shy and a 380 or 9mm is much easier to shoot then a 45 ACP. The military adoption of the 9mm also had an affect on 45 ACP popularity. There are other reasons (9mm is a "cool" cartridge), but the 45 ACP hasn't gotten "worse" just surpassed by a small lighter shooting, mega magazine capacity, 9mm pistols...