Do you honestly believe Keynes' point with this pithy aphorism was that short-term plans are always superior to long-term plans? The fuller quote is "But this long run is a misleading guide to current affairs. In the long run we are all dead. Economists set themselves too easy, too useless a task, if in tempestuous seasons they can only tell us, that when the storm is long past, the ocean is flat again.". He was pushing back on the use of a theory of long-term economic equilibrium in predicting day-to-day conditions, not expressing a preference to screw one's grandchildren over for present gains.