MEngr, I think what you may be calling "interesting" I might consider a "problem". but I do agree with all your points other than what is 'interesting'*.
I try to use some concepts that may be easier to grasp; "Low resistance is only telling the tech that there is a potential path for current to flow" I may say as 'testing the ability of a circuit to carry 1000 watts with a tool that only checks the circuit with milliwatts may not be all that accurate" or that "The real problems are created by current flowing in systems and areas it shouldn't be happening" I might have expressed as "sometimes the path of least resistance at.01 watt may not be the same path of least resistance at 1000 watts", but I kind of think we are making the same points, more often than not.
I do take your point about the more modern trucks having greater egress ratings, and therefore not being any where as susceptible to frame leakage.
I also wonder if our audience recognizes the apples and oranges of your comparison about A/C trucks then your comment about an IGBT. (or is there an A/C truck somehow using IGBTs, that I just have never heard of or considered exactly how that might work out?)
I also hope everyone catches on to the idea that the frame leakage testing is not done as a specific repair for a specific problem, but is more a check in case proper maintenance has not always followed the unit you are working on.
Proper maint. would include battery removal and cleaning, as well as cleaning and keeping clean the battery compartment.

*=?did you watch too much ot the original Star Trek series, and decide you wanted to be just like Mr. Spock? He always thought things that were problems to be solved were "interesting"?
;-)