filial piety is a load of horse shit

It is horribly unethical if parents have kids with the expectation that these kids will one day take care of them. Because the kids had no say in the matter to be born. If the kid was not born, it would have no notion of any of this.

It is like making an unborn kid sign a social contract that it has no awareness of. Then hammer the kid on a daily basis of this social contract. Guilt the kid into obeying.

Use it as a cudgel every time something does not go the way the parents want. Saying how much effort it was to raise the kid, and how ungrateful the kid is for not doing things the way the parents want.

Having a kid is a guilty pleasure.

Having a kid is a genetic nudge.

Having a kid is a social obligation. 

The parents love their kid. Would you subject someone you love to this?

Societally, it is beneficial. It is clearly beneficial to the parents.

The kid should be given the choice, and have that choice be available at all times (when they become adults) whether to exercise filial piety.

Any inherent expectation is unethical.