On some of the harder Maps you´ll get no herbs. and rely on traders is a terrifing thing. you need them for level 2 houses and if you´re unlucky an no one has them for trade over some years - god bye level 4 houses and welcome back to level 1…
So why not give the Gatherer with an Upgraded Building ( Tier 3 / Herbalist) the Option to plant Herbs like the Hunter with traps? Maybe even medical roots with an second Tier 4 upgrade?