Mostly they have not been commercially successful because they don't provide the claimed benefits for most people, have significant disadvantages that outweigh the benefits, and/or are subject to massive failure or huge wear losses after they have been in use for a while.
Certainly, one of those "horsemen of the apocalypse" that I had experience of, the elliptical chainring, deserved its commercial failure. It sounded plausible to the innocent but was technically misconceived.
Furthermore, I can understand why the automatic gearbox in the full implementation (Shimano Di2 for hub gearboxes, with active suspension driven off the same electronics, the "Smover" combo) failed: once you already have an easy-changing manual hub gearbox (Shimano, SRAM, Rohloff, more) the advantages are subtle. But they are there: you cycle more efficiently (by being always in the right gear and being in it sooner) and you arrive in less time and you're fresher when you arrive. But cyclists, even the rational Dutch, didn't see that as worth a premium. I bought my Trek new, landed, for less than the best Gazelle cost, and received wonderful support from Trek Benelux. I thought it was the bargain of all bargains for a technofreak cyclist. (Those who're wondering what we're talking about can find a description of this rare and wonderful bike in the PDF
Andre's Trek Navigator L700 "Smover" available at
my bicycling page.)
As for the Cheeko90, if used as intended, as a seat for bolt upright riders cruising the bike paths of Central Park, it is brilliant. It is even brilliant for the lanes. It has its niche.
I understand, intellectually, what the saddle nose is theoretically good for, but I don't hover over my saddle like a racer down on the drops, I sit squarely on it, and my bike was designed from the ground up, with for instance 14 evenly spaced gears, so that I need
never stand up on the pedals. I therefore don't need the nose, and found the Cheeko90 good in practice regardless of its condemnation on theoretical grounds totally irrelevant to the Cheeko90 design aims by people with zero on-seat experience.
I replaced the Cheeko90 because the materials used on it started to look a bit tacky after a few years. I replaced it with a Brooks saddle because I'd bought one cheap at a monster half-price sale SJS had a few years ago. I kept the Brooks because it is durable and presentable even when worn. But if I could buy a Cheeko90 covered in Brooks-thickness leather today, my order would be in before another five minutes elapsed, at any price up to 140 British pounds, the current new price of the Brooks B73 I use.
Great if they work for you, but "one swallow does not a summer make" 
Too true, but I'm not trying to make a summer, merely to discover what works for me. There is far too much dumb conformity, and pressure for more dumb conformity, in cycling already. (Most boutique gear isn't technically different: it is just snobbishly exclusive, ostentatious spending on the same thing with a fancier label.) That's one of the pleasures of this conference, that the contributors are willing to try anything at least once if it makes some kind of sense, so that someone on here, sometime, tried almost everything which has a true advantage under real-life conditions, and can render a reliable opinion.
