A number of years ago, when I was in marketing for the commercial aviation business at AlliedSignal (now Honeywell), I made a lot of presentations to folks that they shouldn't bet the farm on the Airbus A380 because it made no sense. I didn't think it would ever get built. Well, very few people in the aviation business wanted to hear this. Most people in aerospace are airplane guys first, and business guys second. They wanted this plane to be built and longed to be a part of it. I left before everything was finalized, but my sense is they went off and spent tens of millions of dollars to develop products for the A380.
Well, I was right and wrong. The plane still makes little sense, but it will get built. Maybe. Someday. What I underestimated in the latter question was the willingness of European governments to push the plane against the headwind of economic reality merely as a grand salve for the European ego.
What was wrong with the plane is still wrong now. The original logic, which the company still parrots today, was that airport congestion would require larger and larger planes. If airports are at capacity, in terms of the number of planes they could handle, the planes have to get larger, right? Well, no. The problem with the larger plane is that the FAA and other air transport regulators will require the larger plane to have larger spacing with trailing planes (the larger the plane, the more they create turbulent air and very stable wingtip vortices that pose a danger to trailing planes). In fact, regulators are going to force double or triple the spacing behind the A380 that is required of the 747. How does the plane help congestion, then, if it holds twice the people but takes up three times the landing capacity? Answer: It doesn't. The same arguments can be made where gate space is at a premium - loading and servicing times for the plane can be expected to be twice as long as a regular plane, so in effect it takes up double the gate capacity.
Postscript: The alternate strategy to deal with congestion is to start to abandon the hub and spoke system and move to a point-to-point flight network using smaller planes and involving more airports. This takes connecting traffic out of overloaded hub airports. Its the way the market has been moving, with competitors like Southwest and JetBlue developing point-to-point networks. Asia may be the exception to this development, and it is no accident most A380 orders are Asian airlines.
While I am patting myself on the back, I also said that the Boeing Sonic Cruiser made no sense. The engine and body/wing technology that would make the Sonic Cruiser could either be applied to generate more speed at constant fuel consumption or to achieve current speeds at greatly reduced fuel consumption. I predicted that 10 out of 10 airlines would prefer the latter. And that is the way it played out, with Boeing dropping the Sonic Cruiser, the more monumental and sexy project, in favor of the unsexy but demanded-by-the-marketplace next generation fuel efficient mid-sized aircraft.