...my observation is the rescue course often causes an attitudinal and confidence-boosting transformation in divers that is very positive in net effect...
Absolutely. When I took Rescue with about 40 dives in 2002, I had just begun to venture out diving with just buddies rather than in courses or on shop-run dives.
During the Rescue course, one of my instructors showed me how to use leverage rather than strength to rescue my self-confessed 300 lb "victim" who was told to be a dead weight. Another petite girl and I had already chosen each other as buddies and one of the other instructors said, "Oh no, you're not", and re-assigned us.
With the other instructors tips, I managed to rescue that buddy multiple times and "passed with flying colours", against any odds that may have been bet.
The Rescue course was hard, but so much fun and very rewarding. My situational awareness increased greatly, I was more aware of other divers attitudes and behaviours, I believed I developed the ability to self-rescue, and I gained more confidence as a diver. One of the most important concepts I learned was to not become a second victim. It sounds easy, but in the heat of a rescue, it involves quick decisions and reassessments to find a balance between helping someone and becoming a second victim.
Rescue was one of the courses that I learned the most from.