Complicating things is the fact that for the fist 10+ years, children are extreme burden, so the "transgenerational exploitation" is actually done by the younger generation, even if they didn't mean it. That's the cost of bringing them into existence. It's not fair for parents to keep their children forever in their debt, but let's not pretend we don't owe anything to our parents and their generation either.
It's selfish to demand your children be personally responsible for you.
Making young people miserable under the crushing weight of caring for themselves and their irresponsible elders won't inspire them to produce and share grandkids.
You are right that there should be no crushing weight inflicted. Not all of Japanese worklife has the exploitative nature described upthread. And indeed, seems to be decreasing significantly from the 1980s. For instance, the following situation is no longer likely:
"A boss is working late, so the employees under the boss keep working without being requested to. If the boss disagrees with their decision to stay, then instead of directly telling them they may leave (because they may feel obligated politely refuse as long as the boss is still working), the boss will 'go home' by walking around the block. This gives the employees time to leave, before the boss returns to continue working late."
Consider that in Japan, doing what is best for a group of which you are part is more important than self-interest. There is some modern trend to a little more individualism, in part as reaction to some past and current excesses, and somewhat due to influences of foreign cultures. In general, it seems to be trending toward balance while still keeping a lot of importance of your in-group.
It should be unidirectional giving. Give to your children, and save for yourself. Retire to an assisted living facility, don't become a burden. Hope to die as soon as you become a burden. If you decide to die, because you are done living, I firmly believe that you can die.