What you are really talking about are unfunded liabilities decades away. Suggesting that more people paying into the system could have solved it ignores the fact that, eventually, they too would withdrawal from it. An extra generation could just as easily have contributed to that problem and there’s no point in speculating on what might have been. At best, it pushes the problem down the road and doesn’t solve anything. The problem isn’t that there aren’t enough people paying into the system; the problem is that the people we do have in society are living longer and aren’t paying enough.
I think people are looking at this particular story in the wrong way. The Japanese have very different concepts of life and death. For them, its not a lack of money; wealth in Japan is more prominent among the elderly than any other age bracket (I also read an article at one time stating that they possess half of all privately held savings.) For them, suicide is a matter of pride and honor. Unlike Western values, keeping them alive through futile efforts would be seen as an affront to their dignity. They don’t want to be a burden on their families or the rest of society, whether real or perceived, and Asian culture in general views suicide to be a noble thing. Its why so many of the elderly volunteered to be part of the “suicide corps” that went into the damaged nuclear power plant at Fukushima.