You echoed one of my favorite suspicions. Here's how I look at it: when my '68 fastback was sold new, it retailed for about $2700 brand new. Since my car was sold on Dec 31, 1968 I'm assuming it was a leftover and as such it lke likely sold for less. When I was in high school about ten years later, in 1978 my car would have been worth about the same as when it was brand new, that is, $2000 to $2500 or so. I bought it in 2001 for $7,200 and would have paid more if I had to. At that time the car was 33 years old. Now fast forward to 1988 when my '88 GT 5.0 was new. It cost $16,000 new and has every available option, including the rare T-Tops which were never really offered in '88 but a few were built from leftover '87 bodies, which makes it fairly uncommon. Ten years later the car might have been worth $5000 on a good day. Presently the car is 18 years old and in very good condition. It's never been wrecked and since the car sees very little use, and mostly by my wife, it's never been abused. Know what it's worth today? About $2500, give or take a little. My theory on this is lack of emotion over them is because of the complexity of computer controlled, EFI cars. I feel that the more electronics in anything, the less character or soul that thing has. Nobody gets emotionally attached to their laptop do they? How about your VCR? Nodoby gave a flip when they went out because they were replaced with something better. Same as the Fox-bodies 5.0 Mustangs, the cars that followed were better looking, rode better and were faster, so even though the Fox-bodied cars were the cars that brought back the modern musclecar to America, nobody cares these days. They are busy buying better cars and discarding the older ones. They are too complex for Joe Average to restore with his kid in the garage, so out they go. Ever see the wiring harness in a late '80's Mustang? Looks like something out of the space shuttle, doesn't it? Look under the hood, there's more stuff under there than you can shake a stick at, and none of it looks racy or interesting does it? And don't even think that bolting on a set of aftermarket valve covers is going to make it any better, even if it did, you hafta disassemble the EFI to even get to the valve covers!
Harley Davidson ( my least favorite bike) has made a national treasure out of selling easy to work on, easy to personalize bikes. Are they high tech? No. Are they fast? Get real. But guess what? Any idiot that can find the sharp end of a screwdriver can wander over to a parts catalog, pick out an aircleaner he (or she) likes and install it with no college degree, no shop manual and no special tools needed. Same goes for swapping a cam out of a Harley, I'll bet most of us have the needed tools in the wife's kitchen drawer to swap cams in a air-cooled hog. Guess what, people of all kinds are falling all over themselves to buy overpriced H-D motorcycles so they can personalize it, make it "theirs" by bolting parts on it in their own garage. Anyone remember when new cars were that simple? I remember when the most complex new car in my hometown was a '69 Superbee with three dueces. I'm dead serious. Nobody took their cars to the shop to have them worked on then, yet when I open the hood on my late model Suburban, I don't see anything in there I can trouble shoot. When it fails, it's off to the dealer. Not my wife's '69 Corvette or my '68 fastback. I know every inch of those cars and have rebuilt everything so far anyway, so what's left to fail? Know what else? The Suburban had been on a slide-bed tow truck twice by the time it had 60,000 miles on it. Each time it was for an expensive, high tech parts failure. You want to get attached emotionally to a car lie that? Neither do I, which is why the day of collector musclecars will always be limited to the cars that are already considered classics. Bet on it.