But we generated such massive numerical wealth doing it. That must have been worth it.
Nah, but they'll study the systems and their incentives that led to such actions. Or they'll be more focused on finding food and shelter.
We have limitless power from fission power and solar. There is no reason to ration electricity.
We do not have limitless power today, and much of the power today is being generated by carbon producing means which exacerbates the climate crisis. So yes, there is plenty of reason to not squander electricity today.