Here's a test for all you 50+ers who have been riding since the 70's or before. Can you think of famous component lines that appeared, then were quickly withdrawn?
For example, I was commenting the other day about Shimano producing their track stuff with a 144 bolt circle, and mentioned that they'd probably learned their lesson from the failure of their 10mm-pitch track ensemble back in the late 70's (as I recall). Remember 10mm pitch? You needed to get new chainrings, 10mm-pitch chain, and new cogs. Talk about getting locked in! But they did get some track pro's of the day to use it. As long as it was free, why not?
Shimano was (is) famous for trying to lock you into their gruppos. Remember the old Dyna-Drive pedals? It DID NOT use the standard 9/16 pedal threads, so you had to buy new cranks to use them. I think the gruppo was part of the "AX" (aerodynamic) series, which included an aero center-pull brake, something like Campag's Delta brake.
Campagnolo also came out with some notable failures, including what I think was the worst pedal ever made: the SGR. Very heavy, designed to lock in one position until you got clipped in. And then you were clipped in pretty permanently!
One discontinued Campag component I did like was their Cobalto brakes. The locknut was finished off with a blue plastic "cobalt" stone piece of trim. Totally unnecessary and completely non-functional, but did it ever look sharp! You can buy old Record Cobalto brakes on ebay, but they now cost way more than they did originally! Somebody gave me a couple of the cobalt nuts, which I put on regular Record calipers. Unfortunately, the bike was stolen in Prague...