Nick,
I agree there is usually a good reason ideas are not successfull. But what about the evolution of technology?
The Fairey flew when I was born and your only material choice was aluminum. Could an application of modern aerodynamics, materials and controls help resurrect a design that wasn't profitable at the time?
A good example of technology making an idea work is the submarine. Jules Verne wrote of it, some crazy civil war engineers built one, the Germans made it almost usefull, but it couldn't truly succeed until nuclear power was available.