Right now, burning fuel in the Hearth for resolve scales upwards massively as population goes up. 1 burned fuel gives more resolve the more citizens you have.
A change in this mechanic to reduce the hostility level of the world when you are sacrificing fuel, gives you a way to counter negative resolve during the storm events, and generally even during glade events, without making it almost mindless to just burn fuel to get everyone's resolve into the high 50s and win.
There's some value in getting your fuel levels up to the point where you can just burn your way through the last one or two reputation points. Once you're at a certain level of economic development, the game becomes a bunch of tedious micromanagement, and having the option to burn your stockpile of 400 coal in order to get to what is already an assured victory can take some late game tedium away.
I feel like this could be a great way to introduce a new item or resource, or a new use for an old one. Perhaps burning incense in the hearth reduces hostility, or you can find Effigies in glade events and caches that can be burned to give a bonus for a while.
This is consistent with the intention that sacrificing should be used to bolster low resolve, and provide small meaningful boosts to high resolve to tip over the threshold for reputation gain, while still not making it the sole method to achieve ludicrously high resolve for no other investment, especially late game.
However, it is worth noting that this would be a strong nerf to Forest Mysteries, which scale off hostility level. There may be other interactions and effects from this change which would need further balancing as well.