I hear what you're saying, Rebel_56, but if you're going to ride a bike to work on salted wintry roads, or if you weigh 250lbs and ride hard offroad, you might not want to do it on an irreplaceable piece of historical "art", right? Just last night, I rode a 2008 Worksman (frame and many other parts made in America, BTW) to work and back; I took "the long way home" and bombed some trails on it (fenders and all) to see how my dynamo lights would fare in the woods at 10:30pm. (Visibility was pretty good!) Aside from some mud, everything turned out ok, but what if it hadn't? I'd feel like crap if I'd crashed and bent or snapped something, had it been a nice prewar bike. I tend to prefer the Worksman bikes to the imported industrial bikes, but I'm using these things as tools for commuting and trail-riding, not as collectors' pieces or show bikes. One of the first rules of RRB is you don't talk about the definition of "RatRod", but if you want to do something on the cheap with items on-hand, retired industrial bikes fit the bill for many of us, whether they're domestic or imported...
As for modern steel versus old steel, I definitely agree that things have changed, and that the old steel commonly used for frames and components was often harder/better than the modern stuff. But, a lot of metallurgical advances have been made, and most quality components will be made from aluminum rather than steel.... and high-end steel tubing of today is light-years ahead of most everything they used for frames back then. The flip side is, the cheap hi-ten and mild steel of today pales in comparison t the steel most often used back then. So, comparisons are hard b/c changes in technology and the bicycle market have almost created an apples to oranges situation. But, yeah, the steel that comprises the modern industrial bikes' frames is bottom of the barrel, but they compensate by using plenty of it-- Heavy duty, with the emphasis on "heavy".
Anecdotally, when the Transition bike guys were riding old cruisers and Industrial bikes offroad, before they came out with the Transition Klunker model, they found that the modern SHD and Worksman INB frames were far hardier than the Chicago Schwinns were; the stays on the older Schwinns stretched and sagged to the point where the bottom bracket was measurably closer to the ground. (The one dude from those videos, Thad, was posting on here and remarked at how much of a difference he got when he measured his BB height before and after a few hard rides on an old Schwinn canti frame....)
As I see it, they don't make the old frames anymore, although Worksman is still making their new frames the old way, but I cannot replace a vintage frame if I bend it offroad or if Jersey winters eat thru the metal. I mean, yeah, I can buy another, but that ones gone, and they won't make more. They keep making more Industrial bikes, though, so I see them as the perfect beater: common, cheap, guilt-free, current-production balloon bikes that I can modify and beat on as I see fit, without upsetting anyone. If I bought a '37 Schwinn and klunked it or rode it to work in February, some ppl would be filled with despair. Worse yet, I believe I'd be one of those ppl. So, yeah, I got some older/cooler bikes, but those stay in the garage when it's time to go to work in crap weather, or ride trails. The hard miles go on newer machines; less stressful that way.