TA cages stuck around and stayed in (granted very small) demand for so long because they were one of the best ever for keeping your waterbottle on the bike. The aluminum cages that came about in the '80s were known to shed bottles on hard enough bumps. A properly bent TA never did. I heard (several times over the years) that TA was still making those cages long after they dried u in the US market because pro riders insisted. No, not the names you've heard of. The lowly domestiques on lesser teams who would be far from the team car but had to finish the stage to start the next. For them, a cage that didn't shed bottles could be career saving.

On top of that, really old TA cages didn't break mid-ride. The welds did fail, eventually. But I always noticed this at home. One weld gone. Never had a cage break mid-ride. And I used them for decades and many 10s of thousands of miles. When the source dried up (here in the US), I had to make my old cages go another decade or two until I learned of Chris King's cages.

The crazy TA prices are nuts - now, since you can settle for the excellent SS Chris Kings at $19. But compared to the cages of the 15 years after TA? If keeping your water bottle is a career essential move? Probably justified.

Ben