I'm not serious, these are just the first cynical thoughts that came to mind, but I feel like this question should be one we can actually answer? We've had both pensions and time to see varying degrees of successes and failures regarding them.
And you see why they died out. Y-X consistently became negative as people lived longer, especially when we moved to a service industry. So they ended it and front-loaded the money. There's probably a lieu of tax codes and other benefit they get from matching 401ks as well that I do not know of without researching.