It was DESIGNED for cops to penetrate body armor and car bodies, It never really caught on for Dept. issue, it was considered a "pro's gun", but most civilians weren't professional shooters, and since Dept's didn't want to go to the extra expense it wound up being used by more crooks than cops.
It kind of faded away with the introduction of the .357, and the post war flood of surplus .45's made it kind of pointless.
It seems to have hung on in competition though.