May I suggest also a "travel here" brush? The opposite of the forbidden brush, it causes villagers to consider anything within its path to be desirable over anything outside of it. It would allow villagers to still create their own side-paths organically while also giving users/the Lord/Lady of the settlement the ability to basically say "this is a major road, use it". Brush could also prevent housing from being built there, but that is controllable with the residential brush.
I just think there should be some, limited, ability to guide the villager paths. I love the organic look, most of the time, but I also want some control over major pathways.