@HiBC: What a thoughtful perspective! I have some shooting friends, whose attitude could be improved by reading your post. (Mostly the younger set.)
One virtue of the 300 BLK which has been so far overlooked, is the economy of shooting it, IF you're a handloader. Every range I've visited is literally carpeted with .223/5.56 brass. And I do mean literally. I have so many 5 gal buckets of .223 brass, that most of the time, I don't even bother to pick my empties up.
What you do is spend 40 $ at Harbor Freight for a 2 inch blade, mini metal chop saw. Cut the .223 brass about one blade's width below the bottom of the shoulder. Make one pass into a .300 BLK sizing die, trim and chamfer. You now have a free piece of .300 BLK brass. Years ago, I bought a bulk load of Remington 125 grain, .308 diameter spire points. Never had any use for then until the 300 BLK came along. So, for me, it is just of the cost of powder and primers.
A .300 BLK bolt gun makes a good range toy. I wouldn't want to hunt a 400 pound mule deer with it, but I wouldn't hesitate to use the blackout for a 100 pound Texas white tail.