Another theory
I fully agree that the Cent. Card is a disgrace. No Hyatt, no *wood, no MO any more, no 4 seasons, no IC, no TWA, downgrade of US Air, possibly no more Delta if they are bought. Instead of a person to answer the phone, I am put on hold forever by the same kind of machine every other card gets. In short, Centurion is now just an expensive Plat. card.
I don't really think that Amex is doing this intentionally, though. When Centurion was launched, the travel industry was going through a downturn, and I suspect that Amex got all these perks for nearly free from providers who wanted to court affluent consumers. Now that the travel sector is doing much better, the partners are dropping out. Nobody needs Amex to get booking rates up right now.
It's just a theory, but it avoids the highly specious idea that Amex has a grand plan to screw everybody.