I don't think it's grey at all, what other productive effort do people only do on the grounds that it will enrich their heirs? Maybe that's what it takes to encourage knocking off a king, if that's something you want to encourage, but I can hardly think of anything else.

Still that cuts in both directions, in that you could use it to argue that other properties don't necessarily need to be heritable.

Either way it's pretty clear the "limited times" they were imagining were a portion of a lifespan, not multiple lifespans. It's pretty ridiculous that as the world moves faster these durations are increasing rather than decreasing.