Eric,
You do make some really good points, and the equipment/things you mention suggest that you also have a backpacking or mountaineering background (like I do). I also have a Terraplane pack that I've had since back when Dana produced them in Montana, and that pack is definitely a non-tacticool heavy hauler! In the past I've lugged over 70lbs worth of gear up mountains in this pack, and it definitely serves that role well (and 70lbs of technical climbing equipment, in double plastic boots, when it's -20F and snowing just plain sucks, regardless of pack choice).
I think you also make some good points regarding the skills/knowledge that a lot of folks can pick up through the lightweight backpacking community. These days I rarely use my Terraplane except for winter trips or more involved mountaineering trips. During the other 3-seasons I backpack with a lightweight Granite Gear pack, and can keep my total weight under 20lbs for a 4-day trip (excluding water weight).
As for pack choices, I don't know that I'd automatically eliminate the heavier choices, since an individual's mission may play a big role in deciding which pack to use. My current arsenal of serious packs (bigger than daypacks) includes my Dana Designs Terraplane (5800 cubic inches if memory serves, and 6lbs 11oz on my scale), a Granite Gear Latitude (around 2500 cubic inches from my memory, and 2lbs 8 oz on my scale), and my new Eberlestock Gunslinger II pack (7lbs 0oz on my scale, and 2700 cubic inches per the manufacturer).
Of my packs I'd say that the Terraplane is the best big volume load hauler; it's the largest pack, and has a well-designed suspension system for heavy loads. But, it has no provision for carrying a firearm, doesn't have sufficient attachment points on the outside of the pack for shooting-related accessories, and is a top load only design (except for the sleeping bag compartment -- which will fit my -20F Western Mountaineering bag). My Granite Gear pack is the king of the lightweight packs I've used; it's a comfortable pack, is smaller volume, and is panel loading. But, it lacks a heavy-duty suspension system, and probably wouldn't work well if loaded to more than 35lbs. It's also made out of lightweight materials (read: less durable), and leaves no real provisions for attaching a long gun. My Eberlestock pack is the heaviest of the bunch. It's also made from 1000 denier cordura, and looks like you could drag it behind the car for a while with minimal damage. It is set up with a ton of Molle webbing for accessory attachment. It isn't the biggest pack of the bunch, and is fairly close in size to the Granite Gear pack. But, it's also the only pack of the bunch that is really suitable for carrying a long gun for any length of time. The shoulder straps and hip belt on the Gunslinger aren't as burly as the one's found on my Terraplane, but this also makes me more nimble with this pack on, and it is easier to shoulder a long gun while wearing this pack.
Weight is an important consideration, but the mission often determines the necessary weight of the equipment. My near 11lb mountaineering tent is ridiculously heavy for backpacking in summer, but it is a design that some of my friends have used on Everest, and it has saved my ass a few times in brutal winter conditions on mountains. My 3lb summer tent isn't constructed very strongly by comparison, but it is lightweight, packs easy, and ventilates great in the summer... the mission determines which one of these tents gets loaded in the pack.
But, anyway, you hit the nail on the head with most of your points, and I agree that experience is the best teacher in most cases... I laughed at some of your comments because they're so true: the new guy carrying MRE's and canned food quickly learns why experienced hikers don't. And, the guy who has never carried 50lbs quickly learns why most of us don't like to. But, for an emergency pack an MRE or two isn't always a bad idea, depending on the needs of the mission. Still, a homemade alcohol burning stove, titanium kettle, and a few freeze dried meals often weigh less than a single MRE, and give the user some more flexibility. And, while a lightweight setup is ideal, sometimes weight is unavoidable. Of course, that brings the importance of training back into this discussion!
Your signature line pretty much sums up my 20+ years of backpacking experience, too: "There no comfortable packs, merely packs that are less uncomfortable than others."
In terms of personal opinions regarding bug out bags, I think people also ought to consider the profile they're trying to keep. A civilian backpacking pack is easily ignored by people in a time of emergency. A military-style tacticool camo pack is not so easily dismissed, especially with a gun scabbard, but might provide more opportunities for "disappearing" into the surroundings, and more options for carrying hardware that one might choose to carry in an emergency. Me? I like gear, and I have both types... and I'm not really planning on bugging out any time soon
FINAL THOUGHT: Whenever possible get your pack fitted to you! Wear it in the store with a typical load of gear inside of it, and keep it on for a while. If at all possible, try the pack in the real world before buying it. I've done this with every pack I have (except the Eberlestock -- it was a gift, and that model wasn't around in local stores).