It was pretty standard practice to use 38 Special loads in 357 Mag chambers in the FBI and other agencies at that time.
And yes, it appears most students of the debacle and its aftermath agree that demonizing the 9mm and 38/357 was not the real lesson that needed to be learned. Fortunately, a lot of people have taken the better lessons of the firefight to heart, and as a result being that LEO's are much, much better armed and trained for gunfighting today than they were 30 years ago.
It wasn't "pretty standard practice". It was what was issued. FBI agents use what they are directed to and the .38 Spec. +P LHP was the issued round of the day for the Smith and Wesson model 13, which was the standard issue weapon. There were other approved weapons, such as the 9mm that one of the other agents was carrying. As I stated earlier, the .38 was easier for female agents to handle. In all fairness, the FBI Load, as the round was termed, was about the most effective conventional .38 Spec. load of the day. How well it did out of a 3" barrel, is questionable. Lots of people think Magnums out of anything less than a 4 incher, are severely handicapped and this load was meant to get up to lower magnum velocities.
This is also what you get when you use psych tests and interviews to weed out anybody who is even sympathetic to the gun culture. My best guess is that nowadays you have tests more geared to anti-gunners who like guns themselves and are more elitist in their gun attitudes than classical anti-gunners who want to eradicate the tools themselves. So you get better trained personnel who are very willing to use that training to confiscate guns from others rather than pacifists ordered to use guns to confiscate guns from others under the guise of all guns being eradicated.
