This has been a pet peeve since it was instituted. Try to find a standard factory 40 S&W load that doesn't meet power factor ... easily. It made even less sense when the 10mm was excluded. With all the folks shooting Limited in USPSA wanting to use one setup to load for their guns I can see the 40 being popular (I'd go that route myself), but quite a few people still own just one caliber of 1911 and that is 45 ACP. Granted, CDP is not exclusively limited to the 1911, as previously noted, but that single action trigger is hard to beat.