It has failed because it relies on people to make rational choices and to save money. To be fair, those were considered reasonable expectations until the last few decades.
You don't need 'investment expertise'. You put your money in a Vanguard index fund, and you don't pull it out until you're done working. With a savings rate of even 10%, you're golden by traditional retirement age.
The main problem I have with .. pretty much every article on retirement ever is this line:
>To maintain living standards into old age we need roughly 20 times our annual income in financial wealth.
Really? Your living standard is entirely dictated by how much money you spend?
I had a conversation with my mother recently about their retirement plans - she's "done the math", and they won't be able to retire until a few years after they planned to. I was somewhat surprised, and asked for details - she apparently can't picture living comfortably on less than $130,000 per year. My wife and I have a comparable lifestyle, and are living on $31,000 without even working hard at it.
My advice to everyone: spend less.
You're chucking great gobs of money at things that don't make you happy; just STOP DOING THAT and you will have enough to retire on by the time you're 50.