Roads seem a bit pointless. Maybe I'm missing something, but there never seems to be a good reason to have them. Copper ore roads may be an exception but they still mean time, space, and resources for an advantage that might never actually play a role.
So, suggestion: A dirt/stone/copper road that connects two hearths gives +0.5/1/1.5 global resolve and +5/10/15 hostility.
Welp. I had a suggestion as well about having road connections to ancient hearth give global resolve bonus, but when I clicked the thumbs up button to send it, it deleted it all. So now my suggestion is to fix the comment box deleting itself instead.