I disagree about it being useless. Even with the improved looting added within the last year, just cutting oil upgrades in half for buildings like factory, fort, or missile silo is a huge benefit. You can often age up and immediately queue those upgrades without having to upgrade your refinery for increased capacity first. I also save many millions in gold and food by upgrading lots of walls during rush periods.
That said, worker and time discounts are always welcome, though I have no reason to think they would ever make that part of the seasonal rush periods. People buying crowns and speedups to cut time is how the company makes money.