I have a lot to say about this one. First and foremost, I couldn't agree with you more on the "spray & pray" mentality. In my day of being LE, a very brief day I might add, we did not have semi autos readily available. Some neighboring departments issued the new S&W semi auto 9s. We had wheel guns with a minimum two speed loaders hanging on our belt. We trained, practiced, and drilled relentlessly because the spray and pray option didn't exist. You had 6 shots. Every single one had better count.
As for the "stopping power" argument - As most before me have stated, shot placement makes all of the difference in the world. I have zero doubt that I can effectively defend myself with a 9, 45, 357, etc. However, one study most of the pundits avoid talking about discusses the mental impact of being shot. This article touched on it but didn't really peel the onion back. I speak from experience in that during my short lived LE career, I was involved in three shootouts and sustained gunshot wounds in two of them. Jokingly nobody in the department wanted to be a backup on any of my calls because I seemed to always end up on the calls that ended 11-99.
What I can tell you from experience is that when you sizzle 4 rounds of 9 through a hopped up tweaker, more times than not he'll keep advancing. However, hit the same dude with 2 rounds of 45, he goes into shock pretty quickly. In, or about 1995ish, the S&W Model 457 was approved for carry by my department provided you could qualify with it. I've carried a Model 457 as my EDC since the first time I personally witnessed the difference between the 9 and the 45 when trying to drop a hopped up tweaker.