There is a very good reason the Big Three stopped making full size cars of the kinds they were making at the very end: These cars were obsolete.
Sure - I have no doubt that there are a few people - and likely some people on this thread - who will defend these cars. I'm sure there are also sincere Yugo fans too. But the truth of the matter is money talks, sales are important, and when you're a company that wants to survive, then you've got to get with the program. How wise is it to continue to produce ancient cars with dated styling, with increasingly lower sales? If that's the way a business is run, they will be out of business. This had absolutely NOTHING to do with Cafe standards, so we can put that to rest. It had EVERYTHING to do with consumer preferences.
Secondly, I read an awful lot of auto magazines and web sites, and to sit back and say that the full sized cars the Big 3 made towards the end were competitive is sort of a joke. These cars were basically obsolete and not taken exactly seriously in the automotive press. Again - if you want to stay in business, you have to offer products that sell well.
But you want to know what really happened to all those huge cars? I believe someone else already mentioned this: SUVs and full size trucks basically became the modern day equivalent. Simple.
Lastly, I'm not sure what sort of notion that new gadgets are "gimmicks" or whatnot. If we're going to use that sort of comparison, then might as well make it a progressive argument: If LCD screens are gimmicks, then were CD players? What about power steering? What about power seats, windshield wipers, turn signals, ABS brakes? Why don't we take it back even further? What about electric start? All of those above were at one time newly introduced features. To say that somehow some of the 70's land yachts were innocent of gimmicks is a understatement: Those cars were FULL of gadgets. Remember the Caddy that had the rain-detecting wipers? Yeah - that was in the 70's... remember? It's called technological advancement.
There is also the trend of the times. People will return to a design for the retro appeal with modern technology.
I collect cars. I can actually envision the return of the station wagon for example. I like the long low wheelbase for distance driving. Its car like appeal and driving position, but with some updates.
I remember Lee Iaccoco and the minivan introduction. I had one of the first Caravans. Now I see the minivan as dated. I certainly do not like driving one. I own a crossover, and even now I wish I had a wagon again or a full size car.
I like full size cars, especially for business. And a large trunk. They ride great, lots of room. I had full size SUVs as company cars. Went a bit smaller due to fuel expense. I drive 50000 miles a year with work alone. The SUV and crossovers are a pain carrying things. Parts and equipment slide, make a noise, and some even smell in the cabin with lubricants etc. I did not experience that with full size cars and large trunks. I carry thousands of dollars of tech equipment, and even with dark tint windows, it's less secure.
People buying large vehicles have kids and grand kids to ride along. Not everyone wants to drive an Expedition. I see the return of a fuel efficient full size car and even the wagon in the future. For us that drive a lot, they are a lot nicer to drive than a wallowing SUV.
Trends go and come back again with new styling twists and amenities. Don't count any car design out forever. I love the new Challengers, and I bought one of the first C5 Vettes due to the return of the trunk and the seat center waterfall design from the past. And have bought more since. These design cues keep up buying personal or selection of business vehicles. I nearly live in a car daily, so it's just as important to me as one that's in an office all day.
Windshield wipers, ABS, and turn signals aren't gimmicks, they're necessary features that prevent accidents. Now built-in internet, built-in computer, and built-in movie players are for the most part just gimmicks designed to get younger buyers and raise the MSRP.
And of course the big cars became obsolete near the end. Look at the Town Car, Grand Marquis, and Crown Victoria. There was no incentive to buy one in 2011 when you could just run out and buy an older one (which was basically the same car) for tens of thousands less. They became a joke (especially the Town Car) and received no updates since 1998. Had Ford actually invested into making these things more competitive and actually real luxury cars, rather than just cash-ins, they could have actually been worth looking at.
CAFE standards would have done them in anyway, but Ford could have made these vehicles decently efficient to pass. They had the money and the technology, but they lost interest in selling these cars to actual people, and decided to milk the livery and fleet market.
Look at vehicles like the Rolls-Royce Silver Seraph, and imagine if Lincoln had something like that in their lineup these days for a reasonable price (a lot of the technology in those vehicles is quite modern too). That would be THE car to own for well to do Americans, and would definitely be a good image builder for Lincoln with their tattered image. SUVs would still have a good market, they've been around for a while and always have enjoyed good sales. Plus they (like trucks) enjoy relaxed fuel economy standards from passenger cars, which make them more profitable to field and sell than traditional cars.
But I'm telling you. With good and stately designs, better materials, and better technology (Ford should've lost the ancient air suspension system and replaced it with a more modern active suspension system in the big cars years ago), Ford could have stabilized and increased full-sized car sales. But hey, it's always easier to simply milk these things for all they're worth with the easiest market (fleets have to rebuy these cars every 3-4 years under contract).
But the point is that there is nothing on the market that offers what those of us who liked these cars want - very low price, very durable, with loads of room, comfort, and safety. It doesn't matter if they were 'obsolete' or not, they were better for use. The idea that newer is better is a delusion.
For example - the cast-iron pushrod engine. Yes, it is producing considerably less power per liter, and it doesn't rev up as the 'automotive press' likes, but it lasts far longer and costs far less than the multi-valve one for the glaringly obvious reason - that which is simple is less likely to break than that which is complex.
In point of fact, it is much more apt to be poorly thought out regulation that leads to 'innovation', than any actual demand of the marketplace.