HITC I understand your reasoning with this and think it is more related to the the earlier days of the AUF when only the more dedicated flyers built and flew their planes and engine failures were more common.
Now days with RAAus marketing flying similar to cartons of milk in a supermarket, GYFTS and such, things are different. I think the demand for engine off ops would be relatively quite small and more of interest to people like yourself.
I have had people ring me and ask what I require in a BFR and when I say I like to see throttle off glide approach / simulated engine failure I never hear from them again.
Some time ago I was involved with a thread on here about this that got a bit heated about glide approaches it was after a plane had crashed into the water and the pilot was killed. At the time I was getting concerned about how many prangs we were having in what looked like places they should not have.
The vast majority of people reckoned powered approaches were the way to go. When I said during BFRs there were people with very poor skills at doing simulated engine failures it was suggested it was up to me to to turn around years of poor flying habits during a BFR.
I learnt to fly in a aircraft which had to to be hand started and on a short strip surrounded by tall timber and I had no intention of shutting down the engine.
My preferred method is to reduce power slowly and fly base and final without using the throttle, aim to be high and slip it off when you think you are sure you will make it. This has worked for me just fine over many years but probably not if I had to be in the circuit with others doing half power approaches from a couple of miles away.
If you choose to go slope soaring / thermaling without power and do not have any problems where is the the issue?