Understood, and I think I agree with all your points (wow!)
One point that may be lost in this, one I think you get but I don't want to confuse others with. My walk away splits work for me because I am NOT trying to create lots of queens, but instead lots of colonies. Your point that this is not the most efficient method of rearing queens is spot on. Were I to need to rear queens, I would go back to grafting.
I do try to control the mating side of this equation. I have a yard that is surrounded by three yards of some of my best performing hives (They are from 1 to 3 miles away from the mating yard.) I try to take the majority of my splits there for mating, but I do place others throughout my operation in an attempt to keep the genetics diverse.
I think it's most important to emphasize that while these walk away splits do work for me, you have to put some thought into how you go about doing them and what kind of results you are looking for. Also you must consider your location and whether the time is "right" for making these splits.
Great points; I wouldn't want someone to read my posts and think this was an easy endeavor and then be disappointed.