You make very good points.
Most of my reasoning is based on personal preference. For the time being, I'm not quite motivated enough to keep detailed records. It sounds like you, on the other hand, keep very detailed records - out of necessity. Because of the number of different loads that you use, it makes sense to keep track of everything. For me though, I basically use one bullet weight (168), loaded to roughly the same velocity regardless of the powder used. When I do change bullet weights, it's never a drastic change. Twelve grains up or fourteen grains down. It's easy to keep track, in my head, of the necessary changes in elevation between these loads.
As far as tools go, I desperately want a Leatherman Surge with their bit kit. It would make life much easier. Recording the number of quarter turns is a good system. I would prefer something where there are marks around the circumference of the piece that the screw goes into and a notch or something on the screw that you can index with said marks.
That's totally me being picky though.
If that's the case, I may have to invest in a supply of rock-set. I had a small packet of it that came with my AAC Blackout Flash Hider, but I'm not sure how much I have left. That seriously sounds like good stuff though. Thank you for pointing it out.
Cleaner burning powder could have a lot to do with a lack of carbon build-up. I'm curious, what powders are you using?
If the screw is stainless steel, that could have a big impact on it as well. The last set screw adjustable gas system I used had a parkerized chrome-moly adjustment screw and gas block. If they'd been stainless, I may not have had a problem.
As far as more AR's coming equipped with adjustable gas blocks, I'm not sure. Market demand drives pretty much everything that's offered. If there are more available, there's obviously a demand. The question is whether that demand is based on an actual need that the majority of consumers have, or whether the majority of consumers just think it's "cool." I honestly have no idea which it is.
You've given me some things to think about.